Faculty Profiles - PHAM NAM HAI

写真a

PHAM NAM HAI

Organization

School of Engineering Professor

Homepage

https://magn.ee.eng.isct.ac.jp

External link

News & Topics

トポロジカル絶縁体による磁性体の超高速磁化反転に成功超高速スピン軌道トルク磁気抵抗メモリの実用化へ加速

2022/04/14

Languages： Japanese

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要点-トポロジカル絶縁体によるスピン軌道トルク方式での超高速磁化反転を確認-ナノ秒レベルでの超高速磁化反転に必要な電流密度を劇的に低減-超高速スピン軌道トルク磁気抵抗メモリの開発加速に期待概要東京工業大学工学院電気電子系のファム・ナム・ハイ准教授、外国人特別研究員のNguyenHuynhDuyKha
高スピン流生成効率と高熱耐久性を両立する新材料の開発に成功超低消費電力な不揮発性メモリの実用化加速へ

2022/02/15

Languages： Japanese

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要点-4.1に及ぶ巨大なスピンホール角と、600℃にも耐える高い熱耐久性を両立する新材料の開発に成功。-スピン軌道トルク（SOT）方式に適した純スピン流注入源を開発。-次世代不揮発性メモリの開発加速へ貢献。概要東京工業大学工学院電気電子系のファム・ナムハイ准教授、白倉孝典大学院生（博士後期課程）、キ
トポロジカル絶縁体と磁気トンネル接合を集積した次世代不揮発性メモリSOT-MRAMの実証に成功超低消費電力SOT-MRAMの実用化へ加速

2021/11/05

Languages： Japanese

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要点-トポロジカル絶縁体と磁気トンネル接合を集積したSOT-MRAM素子を作製。-比較的高いトンネル磁気抵抗効果による読み出しと、トポロジカル絶縁体による低電流密度の書き込みを実証。-電子回路の待機電力を大幅に削減できる次世代不揮発性メモリとして、実用化の加速に期待。概要東京工業大学工学院電気電子系
巨大な一方向性スピンホール磁気抵抗効果を実証従来の3桁高い1.1%の巨大な抵抗変化を達成

2019/12/24

Languages： Japanese

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要点-トポロジカル絶縁体と強磁性半導体の接合により実現-強磁性半導体中のマグノン励起・吸収とスピン無秩序散乱を利用-スピン軌道トルク磁気抵抗メモリーの新しい読み出し原理に期待概要東京工業大学工学院電気電子系のファム・ナム・ハイ准教授とNgu
Paving the way for spintronic RAMs: A deeper look into a powerful spin phenomenon

2019/12/24

Languages： English

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Scientists at Tokyo Institute of Technology explore a new material combination that sets the stage for magnetic random access memories, which rely on spin—an intrinsic property of electrons— and c
トポロジカル絶縁体で世界最高性能の純スピン注入源を開発次世代スピン軌道トルク磁気抵抗メモリの実現に期待

2018/07/31

Languages： Japanese

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高い電気伝導率／スピンホール効果をもつトポロジカル絶縁体を利用　常温でも従来よりも2桁高い世界最高性能のスピンホール伝導率を実現　省エネ化、記録速度／記録密度が向上した次世代メモリ開発に道
A colossal breakthrough for topological spintronics: BiSb expands the potential of topological insulators for ultra-low-power electronic devices

2018/07/31

Languages： English

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Scientists have developed the world's best-performing pure spin current source made of bismuth?antimony (BiSb) alloys, which they report as the best candidate for the first industrial application of topological insulators. The achievement represents a big step forward in the development of spin-orbit torque magnetoresistive random-access memory (SOT-MRAM) devices with the potential to replace existing memory technologies.
スピン自由度を用いた次世代半導体デバイス実現へ大きな進展

2016/12/26

Languages： Japanese

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発表のポイント鉄（Fe）を半導体（InAs）へ数%添加したことによってIII-V族半導体で初めてのN型強磁性半導体[用語1](In,Fe)Asを作製し、電子キャリア[用語2]が存在する伝導帯とよばれるエネルギー帯に大きな自発的スピン分裂があることを見出しました（図1）。このようなN型半導体における強磁性と自発的にスピン分裂した伝導帯構造の出現は、従来の理論では予測できないため、半導体や磁性の物性物理学と半導体スピントロニクス[用語3]に新しい知見を与える重要な成果となります。強磁性半導体が大きくスピン分裂した電子状態を持つことを明らかにしたことにより、スピン自由度を利用した様々な半導体デバイスの設計と作製が可能になり、本成果は今後のスピンデバイス応用に向けて大きな前進をもたらすものと期待されます。

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Degree

工学博士 ( 東京大学 )

Research Areas

Nanotechnology/Materials / Applied physical properties
Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electron device and electronic equipment
Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electric and electronic materials

Education

The University of Tokyo

2006.4 - 2009.3

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The University of Tokyo

2004.4 - 2006.3

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Country： Japan

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The University of Tokyo Bachelor

2000.4 - 2004.3

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Country： Japan

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Research History

Institute of Science Tokyo Department of electrical and electronic engineering Professor

2024.10

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Tokyo Institute of Technology School of Engineering, Department of Electrical and Electronic Engineering Professor

2024.4 - 2024.9

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Tokyo Institute of Technology School of Engineering, Department of Electrical and Electronic Engineering Associate Professor

2016.4 - 2024.3

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The University of Tokyo The Graduate School of Engineering, Center for Spintronic Research Network Visiting Associate Professor

2016.4 - 2023.3

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Tokyo Institute of Technology Graduate School of Science and Engineering Department of Physical Electronics Associate Professor

2014.5 - 2016.3

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Professional Memberships

Japan Society of Applied Physics

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The Magnetics Society of Japan

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IEEE Magnetics Society

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Committee Memberships

国際シンポジウム ISAMMA2024 プログラム副委員長

2024

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Committee type：Academic society

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国際学会 SSDM2024 運営委員

2024

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Committee type：Academic society

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国際学会 ICMBE2024 総務委員

2024

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Committee type：Academic society

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日本磁気学会編集委員会幹事、分野主査 (Editor in Chief)

2021 - 2025

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National Science Foundation Research proposal reviewer

2019

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Committee type：Government

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応用物理学会学術講演会プログラム委員会委員

2016 - 2021

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Committee type：Academic society

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日本磁気学会編集委員会委員

2016 - 2021

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Committee type：Academic society

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応用物理学会代議員

2015 - 2016

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Committee type：Academic society

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Papers

Architecture of 3D magnetic domain wall memory for suppressing bit-shift error

Pham Nam Hai, Takanori Shirokura, Nguyen Huynh Duy Khang

Journal of Applied Physics 2025.12

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0284424

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Giant perpendicular magnetic anisotropy in Mo/Boron-rich CoFeB/MgAl2O4 structure

Zhang Ruixian, Sho Kagami, Daiki Ito, Quang Le, Brian York, Cherngye Hwang, Xiaoyong Liu, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano, Pham Nam Hai

Applied Physics Letters 2025.12

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Language：English Publishing type：Research paper (scientific journal)

<jats:p>Perpendicular magnetic tunnel junctions (p-MTJs) with perpendicular magnetic anisotropy (PMA) are key devices for scaling magnetoresistance random access memories down to ∼10 nm. However, the magnetic anisotropy field Hk of the intensively studied CoFeB/MgO is still about 4–6 kOe for bottom CoFeB, and the corresponding magnetic anisotropy energy coefficient Keff is about 3 × 106–5 × 106 erg cm−3. In this study, we aim to realize a giant PMA in Mo (2 nm)/Co19Fe56B25 (tCoFeB)/MgAl2O4 (4 nm)/Ta (1 nm) stack. By using the Boron-rich Co19Fe56B25 layer in combination with the Boron-blocking Mo underlayer and the spinel MgAl2O4 oxide layer, we can realize giant PMA in CoFeB with Hk as high as 17.5–19.5 kOe and Keff as high as 6.9 × 106–9.4 × 106 erg cm−3. Auger electron spectroscopy depth profiles reveal that the good balance between the Boron-blocking Mo layer and the Boron-sink MgAl2O4 layer results in about 20% of the original Boron remaining in CoFeB, leading to a small magnetization and giant PMA. Our results pave the way for further scaling of MTJs and improved resistance against thermal and external magnetic field disturbance.</jats:p>

DOI： 10.1063/5.0301346

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Realization of perpendicular magnetic anisotropy and high spin Hall angle in topological semimetal YPtBi/Ta/CoFeB junctions

Sho Kagami, Reo Yamamoto, Zhang Ruixian, Ken Ishida, Quang Le, Brian York, Cherngye Hwang, Xiaoyong Liu, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano, Pham Nam Hai

Japanese Journal of Applied Physics 2025.12

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Publishing type：Research paper (scientific journal)

<jats:title>Abstract</jats:title>
<jats:p>
YPtBi is a half-Heusler topological semimetal with a large spin Hall angle and high thermal stability. For application to SOT-MRAM, it is essential to fabricate YPtBi/CoFeB junctions with perpendicular magnetic anisotropy (PMA) and high spin Hall angle, which are challenging due to the unfavorable lattice compatibility between YPtBi and CoFeB. In this study, by inserting a Ta spacer layer between YPtBi and CoFeB and optimizing its thickness, we achieved PMA after 300 °C annealing. Subsequently, through optimization of the YPtBi deposition temperature, composition, and CoFeB thickness, we obtained an effective spin Hall angle of
<jats:inline-formula>
<jats:tex-math>

</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:msubsup>
<mml:mrow>
<mml:mi>θ</mml:mi>
</mml:mrow>
<mml:mrow>
<mml:mi mathvariant="normal">SH</mml:mi>
</mml:mrow>
<mml:mrow>
<mml:mi mathvariant="normal">eff</mml:mi>
</mml:mrow>
</mml:msubsup>
<mml:mo>=</mml:mo>
<mml:mn>1.0</mml:mn>
</mml:math>
</jats:inline-formula>
and an effective spin Hall conductivity of
<jats:inline-formula>
<jats:tex-math>

</jats:tex-math>
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll">
<mml:msubsup>
<mml:mi>σ</mml:mi>
<mml:mi>SH</mml:mi>
<mml:mi>eff</mml:mi>
</mml:msubsup>
<mml:mo>=</mml:mo>
<mml:mn>1.6</mml:mn>
<mml:mo>×</mml:mo>
<mml:msup>
<mml:mn>10</mml:mn>
<mml:mn>5</mml:mn>
</mml:msup>
<mml:mspace width="0.25em"/>
<mml:msup>
<mml:mrow>
<mml:mo stretchy="false">(</mml:mo>
<mml:mi mathvariant="normal">ℏ</mml:mi>
<mml:mo>/</mml:mo>
<mml:mn>2</mml:mn>
<mml:mi mathvariant="normal">e</mml:mi>
<mml:mo stretchy="false">)</mml:mo>
<mml:mi mathvariant="normal">Ω</mml:mi>
</mml:mrow>
<mml:mrow>
<mml:mo>−</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:msup>
<mml:msup>
<mml:mi mathvariant="normal">m</mml:mi>
<mml:mrow>
<mml:mo>−</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:msup>
</mml:math>
</jats:inline-formula>
for YPtBi. The latter is comparable to or even superior to those obtained using YPtBi/Pt/Co/Pt junctions. Furthermore, we demonstrated SOT-induced magnetization switching with an ultralow current density. These results indicate that YPtBi is a promising candidate for SOT-MRAM.
</jats:p>

DOI： 10.35848/1347-4065/ae2030

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Comparison of spin Hall angles measured by spin accumulation, spin–orbit torque, and spin Hall magnetoresistance

Min Liu, Zhang Ruixian, Quang Le, Brian York, Cherngye Hwang, Xiaoyong Liu, Xiaoyu Xu, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano, Pham Nam Hai

Japanese Journal of Applied Physics 64 ( 10 ) 103001 - 103001 2025.10

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Publishing type：Research paper (scientific journal) Publisher：IOP Publishing

DOI： 10.35848/1347-4065/ae096c

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Device applications of the giant direct and inverse spin Hall effect in BiSb topological insulator Invited Reviewed

Pham Nam Hai

Proceedings of SPIE 13586 1358607 2025.9

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Publishing type：Research paper (international conference proceedings)

DOI： 10.1117/12.3062225

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Role of Pt and Bi on the giant spin Hall effect in topological semimetal YPtBi

Sho Kagami, Ohiro Fujie, Daiki Ito, Quang Le, Brian York, Cherngye Hwang, Xiaoyong Liu, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano, PHAM NAM HAI

Japanese Journal of Applied Physics 64 ( 5 ) 053001 - 053001 2025.5

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Publishing type：Research paper (scientific journal) Publisher：IOP Publishing

DOI： 10.35848/1347-4065/adcf68

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Very high Curie temperature (470–530 K) in (Ga,Fe)Sb ferromagnetic semiconductor grown by step-flow mode on vicinal GaAs substrates

Pham Nam Hai, Ken Takabayashi, Kota Ejiri, Masaaki Tanaka

Applied Physics Letters 2025.4

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0227990

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Thermal reliability and spin Hall angle of highly textured and epitaxial Bi_0.9Sb_0.1(012) topological insulator

Quang Le, Brian R. York, Cherngye Hwang, Xiaoyong Liu, Lei Xu, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano, Min Liu, Zhang Ruixian, Shota Namba, PHAM NAM HAI

Japanese Journal of Applied Physics 2025.4

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<jats:title>Abstract</jats:title>
<jats:p>In this study, we examine the impact of various seed layer materials that facilitate the growth of highly textured or epitaxial topological insulator Bi<jats:sub>0.9</jats:sub>Sb<jats:sub>0.1</jats:sub>(012) on Si/SiOx substrates. We found that cubic-textured (100) or tetragonal (001) seed layers facilitate the epitaxial growth of undoped Bi<jats:sub>1−<jats:italic>x</jats:italic>
</jats:sub>Sb<jats:sub>
<jats:italic>x</jats:italic>
</jats:sub>(012) with more square surface, while seed layers composed of (111) polycrystalline or, alternatively, nanocrystalline or amorphous materials are suitable for growth of highly textured Bi<jats:sub>1−<jats:italic>x</jats:italic>
</jats:sub>Sb<jats:sub>
<jats:italic>x</jats:italic>
</jats:sub>(012):X with more rectangular surface (012), where X is a dopant. By post annealing, we obtained a maximum spin Hall angle of 24 for epitaxial Bi<jats:sub>0.9</jats:sub>Sb<jats:sub>0.1</jats:sub>(012). Furthermore, we found a clear correlation between the spin Hall angle and the column height in Bi<jats:sub>0.9</jats:sub>Sb<jats:sub>0.1</jats:sub>(012) subjected to post annealing up to 215 °C and 3 h. Our findings establish a foundation for effective methodologies aimed at producing high-performance Bi<jats:sub>1−<jats:italic>x</jats:italic>
</jats:sub>Sb<jats:sub>
<jats:italic>x</jats:italic>
</jats:sub> in the (012) orientation on practical Si/SiO<jats:sub>
<jats:italic>x</jats:italic>
</jats:sub> substrates using physical vapor deposition.</jats:p>

DOI： 10.35848/1347-4065/adca78

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Effects of metal, oxide, and hybrid metal-oxide interlayers on spin–orbit torque in BiSb topological insulator and magnetic interfaces

Quang Le, Xiaoyong Liu, Lei Xu, Brian R. York, Cherngye Hwang, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano, Min Liu, Zhang Ruixian, Shota Namba, PHAM NAM HAI

Journal of Applied Physics 137 ( 12 ) 2025.3

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Publishing type：Research paper (scientific journal) Publisher：AIP Publishing

DOI： 10.1063/5.0253596

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Spin Hall magnetic field sensing device using topological insulator

Min Liu, Zhang Ruixian, Quang Le, Brian York, Cherngye Hwang, Xiaoyong Liu, Michael Gribelyuk, Xiaoyu, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano, PHAM NAM HAI

Applied Physics Letters 125 ( 24 ) 2024.12

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Publishing type：Research paper (scientific journal) Publisher：AIP Publishing

DOI： 10.1063/5.0233246

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Transport and material properties of doped BiSbX topological insulator films grown by physical vapor deposition

Quang Le, Brian R. York, Cherngye Hwang, Xiaoyong Liu, Michael A. Gribelyuk, Son Le, Lei Xu, Jason James, Jose Ortega, Maki Maeda, Tuo Fan, Hisashi Takano, Min Liu, Zhang Ruixian, Shota Namba, PHAM NAM HAI

Japanese Journal of Applied Physics 63 ( 12 ) 123001 - 123001 2024.12

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Publishing type：Research paper (scientific journal) Publisher：IOP Publishing

DOI： 10.35848/1347-4065/ad936c

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Spin Hall effect in platinum deposited by atomic layer deposition

Ken Ishida, Kota Sato, Pham Nam Hai

Applied Physics Letters 2024.10

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0229825

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Effects of post-growth annealing in YPtBi topological semimetal and Co/Pt perpendicular magnetization multilayers

Sho Kagami, Takanori Shirokura, Pham Nam Hai

Japanese Journal of Applied Physics 2024.2

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Publishing type：Research paper (scientific journal)

DOI： 10.35848/1347-4065/ad1e98

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High spin Hall angle in BiSb topological insulator and perpendicularly magnetized CoFeB/MgO multilayers with metallic interfacial layers

Zhang Ruixian, Huy Ho Hoang, Takanori Shirokura, PHAM NAM HAI, Quang Le, Brian York, Cherngye Hwang, Xiaoyong Liu, Michael Gribelyuk, Xiaoyu, Son Le, Maki Maeda, Tuo Fan, Yu Tao, Hisashi Takano

Applied Physics Letters 2024.2

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<jats:p>In this study, we investigate the spin Hall effect in heterostructures of Bi0.85Sb0.15 (10 nm) topological insulator/Ru(Ti)/Ta/Co20Fe60B20/MgO with perpendicular magnetic anisotropy. By optimizing the Ru (Ti) interfacial layer thickness as well as deposition condition of BiSb, we achieve a large effective spin Hall angle of 6.0 ± 0.1 and relatively high electrical conductivity of 1.5 × 105 Ω−1 m−1 at room temperature. We, then, demonstrate spin–orbit torque-induced magnetization switching driven by a small threshold current density of 1 × 106 Acm−2. Benchmarking shows that the writing power consumption of our stack is 2–3 orders smaller than that of heavy metals.</jats:p>

DOI： 10.1063/5.0184870

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High-efficient spin orbit torque generated by topological semimetal YPtBi deposited on oxidized Si substrates

Takanori Shirokura, Nguyen Huynh Duy Khang, Pham Nam Hai

Applied Physics Letters 2024.1

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0185917

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Enhanced spin Hall effect at high temperature in non-centrosymmetric silicide TaSi2 driven by Berry phase monopoles

Ken Ishida, Takanori Shirokura, Pham Nam Hai

Applied Physics Letters 2023.12

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0165333

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High temperature spin Hall effect in topological insulator

Takanori Shirokura, Pham Nam Hai

Applied Physics Letters 2023.6

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DOI： 10.1063/5.0143287

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Highly efficient spin current source using BiSb topological insulator/NiO bilayers

Julian Sasaki, Shota Namba, Shigeki Takahashi, Yoshiyuki Hirayama, Pham Nam Hai

Japanese Journal of Applied Physics 2023.4

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Publishing type：Research paper (scientific journal)

DOI： 10.35848/1347-4065/aca772

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Room-temperature spin injection from a ferromagnetic semiconductor

Shobhit Goel, Nguyen Huynh Duy Khang, Yuki Osada, Le Duc Anh, Pham Nam Hai, Masaaki Tanaka

Scientific Reports 2023.2

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Publishing type：Research paper (scientific journal)

DOI： 10.1038/s41598-023-29169-9

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Large inverse spin Hall effect in BiSb topological insulator for 4 Tb/in2 magnetic recording technology

Ho Hoang Huy, Julian Sasaki, Nguyen Huynh Duy Khang, Shota Namba, Pham Nam Hai, Quang Le, Brian York, Cherngye Hwang, Xiaoyong Liu, Michael Gribelyuk, Xiaoyu Xu, Son Le, Michael Ho, Hisashi Takano

Applied Physics Letters 2023.1

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0135831

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Integration of BiSb topological insulator and CoFeB/MgO with perpendicular magnetic anisotropy using an oxide interfacial layer for ultralow power SOT-MRAM cache memory

Ho Hoang Huy, Zhang Ruixian, Takanori Shirokura, Shigeki Takahashi, Yoshiyuki Hirayama, Pham Nam Hai

IEEE Transactions on Magnetics 2023

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Publishing type：Research paper (scientific journal)

DOI： 10.1109/TMAG.2023.3275171

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Giant spin Hall effect in half-Heusler alloy topological semimetal YPtBi grown at low temperature

Takanori Shirokura, Pham Nam Hai

AIP Advances 2022.12

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0117613

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Ferromagnetism modulation by ultralow current in a two-dimensional polycrystalline molybdenum disulphide atomic layered structure

Iriya Muneta, Takanori Shirokura, Pham Nam Hai, Kuniyuki Kakushima, Kazuo Tsutsui, Hitoshi Wakabayashi

Scientific Reports 12 ( 1 ) 2022.10

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Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media {LLC}

DOI： 10.1038/s41598-022-22113-3

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Effect of stoichiometry on the spin Hall angle of the half-Heusler alloy topological semimetal YPtBi

Takanori Shirokura, Tsuyoshi Kondo, Pham Nam Hai

Japanese Journal of Applied Physics 2022.7

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Publishing type：Research paper (scientific journal) Publisher：{IOP} Publishing

DOI： 10.35848/1347-4065/ac7834

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Rhombic Fermi surfaces in a ferromagnetic MnGa thin film with perpendicular magnetic anisotropy

M. Kobayashi, N. H. D. Khang, T. Takeda, K. Araki, R. Okano, M. Suzuki, K. Kuroda, K. Yaji, K. Sugawara, S. Souma, K. Nakayama, K. Yamauchi, M. Kitamura, K. Horiba, A. Fujimori, T. Sato, S. Shin, M. Tanaka, P. N. Hai

Physical Review Materials 2022.7

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Publishing type：Research paper (scientific journal)

DOI： 10.1103/physrevmaterials.6.074403

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Nanosecond ultralow power spin orbit torque magnetization switching driven by BiSb topological insulator

Nguyen Huynh Duy Khang, Takanori Shirokura, Tuo Fan, Mao Takahashi, Naoki Nakatani, Daisuke Kato, Yasuyoshi Miyamoto, Pham Nam Hai

Applied Physics Letters 120 ( 15 ) 152401 - 152401 2022.4

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Publishing type：Research paper (scientific journal) Publisher：{AIP} Publishing

DOI： 10.1063/5.0084927

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Improvement of the Effective Spin Hall Angle by Inserting an Interfacial Layer in Sputtered BiSb Topological Insulator (Bottom)/Ferromagnet With In-Plane Magnetization

J. Sasaki, H. H. Huy, N. H. D. Khang, P. N. Hai, Q. Le, B. York, X. Liu, S. Le, C. Hwang, M. Ho, H. Takano

IEEE Transactions on Magnetics 58 ( 4 ) 1 - 4 2022.4

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Publishing type：Research paper (scientific journal) Publisher：Institute of Electrical and Electronics Engineers ({IEEE})

DOI： 10.1109/TMAG.2021.3115169

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Efficient spin current source using a half-Heusler alloy topological semimetal with back end of line compatibility

Takanori Shirokura, Tuo Fan, Nguyen Huynh Duy Khang, Tsuyoshi Kondo, Pham Nam Hai

Scientific Reports 12 ( 1 ) 2022.2

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Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media {LLC}

<jats:title>Abstract</jats:title><jats:p>Topological materials, such as topological insulators (TIs), have great potential for ultralow power spintronic devices, thanks to their giant spin Hall effect. However, the giant spin Hall angle (<jats:italic>θ</jats:italic><jats:sub>SH</jats:sub> > 1) is limited to a few chalcogenide TIs with toxic elements and low melting points, making them challenging for device integration during the silicon Back-End-of-Line (BEOL) process. Here, we show that by using a half-Heusler alloy topological semi-metal (HHA-TSM), YPtBi, it is possible to achieve both a giant <jats:italic>θ</jats:italic><jats:sub>SH</jats:sub> up to 4.1 and a high thermal budget up to 600 °C. We demonstrate magnetization switching of a CoPt thin film using the giant spin Hall effect of YPtBi by current densities lower than those of heavy metals by one order of magnitude. Since HHA-TSM includes a group of three-element topological materials with great flexibility, our work opens the door to the third-generation spin Hall materials with both high <jats:italic>θ</jats:italic><jats:sub>SH</jats:sub> and high compatibility with the BEOL process that would be easily adopted by the industry.</jats:p>

DOI： 10.1038/s41598-022-06325-1

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Ultrahigh efficient spin orbit torque magnetization switching in fully sputtered topological insulator and ferromagnet multilayers

Tuo Fan, Nguyen Huynh Duy Khang, Soichiro Nakano, Pham Nam Hai

Scientific Reports 12 ( 1 ) 2022.2

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<jats:title>Abstract</jats:title><jats:p>Spin orbit torque (SOT) magnetization switching of ferromagnets with large perpendicular magnetic anisotropy has a great potential for the next generation non-volatile magnetoresistive random-access memory (MRAM). It requires a high performance pure spin current source with a large spin Hall angle and high electrical conductivity, which can be fabricated by a mass production technique. In this work, we demonstrate ultrahigh efficient and robust SOT magnetization switching in fully sputtered BiSb topological insulator and perpendicularly magnetized Co/Pt multilayers. Despite fabricated by the magnetron sputtering instead of the laboratory molecular beam epitaxy, the topological insulator layer, BiSb, shows a large spin Hall angle of <jats:italic>θ</jats:italic><jats:sub>SH</jats:sub> = 10.7 and high electrical conductivity of <jats:italic>σ</jats:italic> = 1.5 × 10<jats:sup>5</jats:sup> Ω<jats:sup>−1</jats:sup> m<jats:sup>−1</jats:sup>. Our results demonstrate the feasibility of BiSb topological insulator for implementation of ultralow power SOT-MRAM and other SOT-based spintronic devices.</jats:p>

DOI： 10.1038/s41598-022-06779-3

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Spin transport in fully ferromagnetic p–n junctions

Nguyen Thanh Tu, Tomohiro Otsuka, Yuto Arakawa, Le Duc Anh, Masaaki Tanaka, Pham Nam Hai

Journal of Applied Physics 131 ( 1 ) 013902 - 013902 2022.1

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Publishing type：Research paper (scientific journal) Publisher：AIP Publishing

DOI： 10.1063/5.0072128

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Large spin Hall angle in sputtered BiSb topological insulator on top of various ferromagnets with in-plane magnetization for SOT reader application

H. H. Huy, J. Sasaki, N. H. D. Khang, S. Namba, P. N. Hai, Q. Le, B. York, C. Hwang, X. Liu, M. Gribelyuk, X. Xu, S. Le, R. Nagabhirava, M. Ho, H. Takano

IEEE Transactions on Magnetics 2022

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DOI： 10.1109/TMAG.2022.3215481

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Magnetic memory driven by topological insulators

Hao Wu, Aitian Chen, Peng Zhang, Haoran He, John Nance, Chenyang Guo, Julian Sasaki, Takanori Shirokura, Pham Nam Hai, Bin Fang, Seyed Armin Razavi, Kin Wong, Yan Wen, Yinchang Ma, Guoqiang Yu, Gregory P. Carman, Xiufeng Han, Xixiang Zhang, Kang L. Wang

Nature Communications 2021.12

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Publishing type：Research paper (scientific journal)

DOI： 10.1038/s41467-021-26478-3

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Angle resolved second harmonic technique for precise evaluation of spin orbit torque in strong perpendicular magnetic anisotropy systems

Takanori Shirokura, Pham Nam Hai

Applied Physics Letters 2021.11

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Publishing type：Research paper (scientific journal)

DOI： 10.1063/5.0074629

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Low power spin–orbit torque switching in sputtered BiSb topological insulator/perpendicularly magnetized CoPt/MgO multilayers on oxidized Si substrate

Tuo Fan, Nguyen Huynh Duy Khang, Takanori Shirokura, Ho Hoang Huy, Pham Nam Hai

Applied Physics Letters 119 ( 8 ) 082403 - 082403 2021.8

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DOI： 10.1063/5.0062625

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Spin Hall effect in amorphous YPt alloy

Takanori Shirokura, Kou Fujiwara, Pham Nam Hai

Applied Physics Express 14 ( 4 ) 043002 - 043002 2021.4

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Publishing type：Research paper (scientific journal) Publisher：{IOP} Publishing

DOI： 10.35848/1882-0786/abed8f

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Minority-spin impurity band in n-type (In,Fe)As: A materials perspective for ferromagnetic semiconductors

Masaki Kobayashi, Le Duc Anh, Jan Minar, Walayat Khan, Stephan Borek, Pham Nam Hai, Yoshihisa Harada, Thorsten Schmitt, Masaharu Oshima, Atsushi Fujimori, Masaaki Tanaka, Vladimir N. Strocov

PHYSICAL REVIEW B 103 ( 11 ) 2021.3

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DOI： 10.1103/PhysRevB.103.115111

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Spin–orbit torque as a method for field-free detection of in-plane magnetization switching

Nguyen Huynh Duy Khang, Pham Nam Hai

Applied Physics Letters 2020.12

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DOI： 10.1063/5.0033158

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Direct observation of the magnetic ordering process in the ferromagnetic semiconductor Ga1−xMnxAs via soft x-ray magnetic circular dichroism

Yukiharu Takeda, Shinobu Ohya, Nam Hai Pham, Masaki Kobayashi, Yuji Saitoh, Hiroshi Yamagami, Masaaki Tanaka, Atsushi Fujimori

Journal of Applied Physics 128 ( 21 ) 213902 - 213902 2020.12

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DOI： 10.1063/5.0031605

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Spin Hall Effect in Topological Insulators

P. N. Hai

Journal of the Magnetics Society of Japan 44 ( 6 ) 137 - 144 2020.11

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Publishing type：Research paper (scientific journal) Publisher：The Magnetics Society of Japan

DOI： 10.3379/msjmag.2009rv001

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Ultralow power spin–orbit torque magnetization switching induced by a non-epitaxial topological insulator on Si substrates Reviewed

Nguyen Huynh Duy Khang, Soichiro Nakano, Takanori Shirokura, Yasuyoshi Miyamoto, Pham Nam Hai

Scientific Reports 10 ( 1 ) 2020.7

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Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media {LLC}

DOI： 10.1038/s41598-020-69027-6

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Inhomogeneity-induced high temperature ferromagnetism in n-type ferromagnetic semiconductor (In,Fe)As grown on vicinal GaAs substrates

Pham Nam Hai, Munehiko Yoshida, Akihide Nagamine, Masaaki Tanaka

Japanese Journal of Applied Physics 59 ( 6 ) 063002 - 063002 2020.6

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DOI： 10.35848/1347-4065/ab9401

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Crystal growth and characterization of topological insulator BiSb thin films by sputtering deposition on sapphire substrates

Tuo Fan, Mustafa Tobah, Takanori Shirokura, Nguyen Huynh Duy Khang, Pham Nam Hai

Japanese Journal of Applied Physics 2020.6

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DOI： 10.35848/1347-4065/ab91d0

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Large magnetoresistance and spin-dependent output voltage in a lateral MnGa/GaAs/MnGa spin-valve device Reviewed

Koki Chonan, Nguyen Huynh Duy Khang, Masaaki Tanaka, Pham Nam Hai

Japanese Journal of Applied Physics 2020.4

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Publishing type：Research paper (scientific journal) Publisher：{IOP} Publishing

DOI： 10.7567/1347-4065/ab5b31

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Bias-field-free spin Hall nano-oscillators with an out-of-plane precession mode

Takanori Shirokura, Pham Nam Hai

Journal of Applied Physics 2020.1 1944 - 1944 2020.3

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DOI： 10.1063/1.5142627

CiNii Research

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Magnetization process of the insulating ferromagnetic semiconductor (Al,Fe)Sb

Shoya Sakamoto, Yosuke Nonaka, Keisuke Ikeda, Zhendong Chi, Yuxuan Wan, Masahiro Suzuki, Atsushi Fujimori, Le Duc Anh, Pham Nam Hai, Yukiharu Takeda, Yuji Saitoh, Masaki Kobayashi, Masaaki Tanaka, Yuki K. Wakabayashi, Hiroshi Yamagami

Physical Review B 101 ( 7 ) 2020.2

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DOI： 10.1103/PhysRevB.101.075204

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Giant unidirectional spin Hall magnetoresistance in topological insulator – ferromagnetic semiconductor heterostructures Reviewed

Nguyen Huynh Duy Khang, Pham Nam Hai

Journal of Applied Physics 2019.12

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DOI： 10.1063/1.5134728

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Zero-field topological Hall effect as evidence of ground-state skyrmions at room temperature in BiSb/MnGa bilayers Reviewed

Nguyen Huynh Duy Khang, Tuo Fan, Pham Nam Hai

AIP Advances 2019.12

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DOI： 10.1063/1.5119758

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Heavily Fe-doped ferromagnetic semiconductor (In,Fe)Sb with high Curie temperature and large magnetic anisotropy Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaka

Applied Physics Express 2019.10

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Publishing type：Research paper (scientific journal) Publisher：Japan Society of Applied Physics

DOI： 10.7567/1882-0786/ab3f4b

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Electronic structure of the high-TC ferromagnetic semiconductor (Ga,Fe)Sb: X-ray magnetic circular dichroism and resonance photoemission spectroscopy studies Reviewed

Shoya Sakamoto, Nguyen Thanh Tu, Yukiharu Takeda, Shin-ichi Fujimori, Pham Nam Hai, Le Duc Anh, Yuki K. Wakabayashi, Goro Shibata, Masafumi Horio, Keisuke Ikeda, Yuji Saitoh, Hiroshi Yamagami, Masaaki Tanaka, Atsushi Fujimori

Physical Review B 100 ( 3 ) 2019.7

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DOI： 10.1103/physrevb.100.035204

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Lateral silicon spin-valve devices with large spin-dependent magnetoresistance and output voltage Reviewed

Duong Dinh Hiep, Masaaki Tanaka, Pham Nam Hai

Advances in Natural Sciences: Nanoscience and Nanotechnology 10 ( 2 ) 025001 - 025001 2019.4

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Publishing type：Research paper (scientific journal) Publisher：{IOP} Publishing

DOI： 10.1088/2043-6254/ab11df

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Influence of crystal orientation and surface termination on the growth of BiSb thin films on GaAs substrates Reviewed

Kenichiro Yao, Nguyen Huynh Duy Khang, Pham Nam Hai

Journal of Crystal Growth 511 99 - 105 2019.4

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Publishing type：Research paper (scientific journal) Publisher：Elsevier {BV}

DOI： 10.1016/j.jcrysgro.2019.01.041

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Fe delta-doped (In,Fe)Sb ferromagnetic semiconductor thin films for magnetic-field sensors with ultrahigh Hall sensitivity Reviewed

Kento Nishijima, Nguyen Thanh Tu, Masaaki Tanaka, Pham Nam Hai

Journal of Crystal Growth 511 127 - 131 2019.4

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Publishing type：Research paper (scientific journal) Publisher：Elsevier {BV}

DOI： 10.1016/j.jcrysgro.2019.01.030

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A conductive topological insulator with large spin Hall effect for ultralow power spin–orbit torque switching Reviewed

Nguyen Huynh Duy Khang, Yugo Ueda, Pham Nam Hai

Nature Materials 17 ( 9 ) 808 - 813 2018.9

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Publishing type：Research paper (scientific journal) Publisher：Springer Nature

DOI： 10.1038/s41563-018-0137-y

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Conductive BiSb topological insulator with colossal spin Hall effect for ultra-low power spin-orbit-torque switching Reviewed

Kenichiro Yao, Pham Nam Hai, Nguyen Huynh Duy Khang, Yugo Ueda

Spintronics XI 2018.9

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Publisher：SPIE

DOI： 10.1117/12.2316612

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Fe-based n-type and p-type narrow-gap III-V ferromagnetic semiconductors with high Curie temperatures (Conference Presentation) Reviewed

Duc Anh Le, Nguyen Thanh Tu, Pham Nam Hai, Masaaki Tanaka

Spintronics XI 2018.9

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Publisher：SPIE

DOI： 10.1117/12.2320144

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Spin-valve effect in nanoscale Si-based Devices Reviewed International journal

PHAM NAM HAI

AAPPS Bulletin 2018.6

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DOI： 10.22661/aaPPSBl.2018.28.3.07

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Planar Nernst effect and Mott relation in (In,Fe)Sb ferromagnetic semiconductor Reviewed

Cong Tinh Bui, Christina A. C. Garcia, Nguyen Thanh Tu, Masaaki Tanaka, Pham Nam Hai

Journal of Applied Physics 123 ( 17 ) 175102 - 175102 2018.5

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DOI： 10.1063/1.5026452

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High-temperature ferromagnetism in new n-type Fe-doped ferromagnetic semiconductor (In,Fe)Sb Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaka

Applied Physics Express 11 ( 6 ) 063005 - 063005 2018.5

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Language：English Publishing type：Research paper (scientific journal) Publisher：Japan Society of Applied Physics

DOI： 10.7567/apex.11.063005

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Electrical tuning of the band alignment and magnetoconductance in an n-type ferromagnetic semiconductor (In,Fe)As-based spin-Esaki diode Reviewed

Le Duc Anh, Pham Nam Hai, Masaaki Tanaka

Applied Physics Letters 112 ( 10 ) 102402 - 102402 2018.3

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DOI： 10.1063/1.5010020

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Electrical control of ferromagnetism in the n-type ferromagnetic semiconductor (In,Fe)Sb with high Curie temperature Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaka

Applied Physics Letters 112 ( 12 ) 122409 - 122409 2018.3

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Language：English Publishing type：Research paper (scientific journal) Publisher：{AIP} Publishing

DOI： 10.1063/1.5022828

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III-V and Group-IV-Based Ferromagnetic Semiconductors for Spintronics Reviewed

Pham Nam Hai

Reference Module in Materials Science and Materials Engineering 2018

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Publisher：Elsevier

DOI： 10.1016/b978-0-12-803581-8.10451-5

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Growth and characterization of MnGa thin films with perpendicular magnetic anisotropy on BiSb topological insulator Reviewed

Nguyen Huynh Duy Khang, Yugo Ueda, Kenichiro Yao, Pham Nam Hai

JOURNAL OF APPLIED PHYSICS 122 ( 14 ) 2017.10

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DOI： 10.1063/1.4999617

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Epitaxial growth and characterization of Bi1-xSbx spin Hall thin films on GaAs(111) A substrates Reviewed

Yugo Ueda, Nguyen Huynh Duy Khang, Kenichiro Yao, Pham Nam Hai

APPLIED PHYSICS LETTERS 110 ( 6 ) 2017.2

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Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1063/1.4975492

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Inverse spin-valve effect in nanoscale Si-based spin-valve devices Reviewed

Duong Dinh Hiep, Masaaki Tanaka, Pham Nam Hai

Journal of Applied Physics 122 ( 22 ) 223904 - 223904 2017

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Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1063/1.4994881

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Ballistic transport in spin-valve Si channel demonstrates feasibility of nanoscale spin-MOSFETs Reviewed

Rachele Hendricks-Sturrup

Scilight 2017 ( 25 ) 250004 - 250004 2017

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Publishing type：Research paper (scientific journal) Publisher：{AIP} Publishing

DOI： 10.1063/1.5018722

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Observation of spontaneous spin-splitting in the band structure of an n-type zinc-blende ferromagnetic semiconductor. Reviewed

Anh LD, Hai PN, Tanaka M

Nature communications 7 2016.12

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Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1038/ncomms13810

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High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaka

Applied Physics Letters 108 ( 19 ) 192401 - 192401 2016.5

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Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1063/1.4948692

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Visible-light emission at room temperature in Mn-doped Si light-emitting diodes Reviewed

Pham Nam Hai, Daiki Maruo, Le Duc Anh, Masaaki Tanaka

Physical Review B 93 ( 9 ) 2016.3

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DOI： 10.1103/physrevb.93.094423

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Magnetization process of the n-type ferromagnetic semiconductor (In,Fe) As:Be studied by x-ray magnetic circular dichroism Reviewed

S. Sakamoto, L. D. Anh, P. N. Hai, G. Shibata, Y. Takeda, M. Kobayashi, Y. Takahashi, T. Koide, M. Tanaka, A. Fujimori

PHYSICAL REVIEW B 93 ( 3 ) 2016.1

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DOI： 10.1103/PhysRevB.93.035203

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Magnetization process of then-type ferromagnetic semiconductor (In,Fe)As:Be studied by x-ray magnetic circular dichroism Reviewed

S. Sakamoto, L. D. Anh, P. N. Hai, G. Shibata, Y. Takeda, M. Kobayashi, Y. Takahashi, T. Koide, M. Tanaka, A. Fujimori

Physical Review B 93 ( 3 ) 2016.1

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Language：English Publishing type：Research paper (scientific journal) Publisher：American Physical Society ({APS})

DOI： 10.1103/physrevb.93.035203

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High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaki

2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS) 108 ( 19 ) 192401 - 192401 2016

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Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1063/1.4948692

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Spin transport in nanoscale Si-based spin-valve devices Reviewed

Duong Dinh Hiep, Masaaki Tanaka, Pham Nam Hai

Applied Physics Letters 109 ( 23 ) 232402 - 232402 2016

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Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1063/1.4971351

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High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaki

2016 COMPOUND SEMICONDUCTOR WEEK (CSW) INCLUDES 28TH INTERNATIONAL CONFERENCE ON INDIUM PHOSPHIDE & RELATED MATERIALS (IPRM) & 43RD INTERNATIONAL SYMPOSIUM ON COMPOUND SEMICONDUCTORS (ISCS) 2016

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Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1109/ICIPRM.2016.7528851

DOI： 10.1109/iciprm.2016.7528851

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Spinodal nanodecomposition in semiconductors doped with transition metals Reviewed

Tomasz,Dietl, Kazunori,Sato, Tetsuya,Fukushima, Alberta,Bonanni, Mathew,Jamet, André Barski, Shinji,Kuroda, Masaaki,Tanaka, Pham,Nam Hai, Hiroshi,Katayama-Yoshida

Reviews of Modern Physics 87 ( 4 ) 1311 - 1377 2015.11

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Language：English Publishing type：Research paper (scientific journal) Publisher：American Physical Soceity

DOI： 10.1103/RevModPhys.87.1311

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Magnetic properties and intrinsic ferromagnetism in(Ga,Fe)Sbferromagnetic semiconductors Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaka

Physical Review B 92 ( 14 ) 2015.10

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DOI： 10.1103/physrevb.92.144403

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Modulation of ferromagnetism in(In,Fe)Asquantum wells via electrically controlled deformation of the electron wave functions Reviewed

Le Duc Anh, Pham Nam Hai, Yuichi Kasahara, Yoshihiro Iwasa, Masaaki Tanaka

Physical Review B 92 ( 16 ) 2015.10

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DOI： 10.1103/physrevb.92.161201

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Memristive magnetic tunnel junctions with MnAs nanoparticles Reviewed

Pham Nam Hai, Masaaki Tanaka

Applied Physics Letters 107 ( 12 ) 122404 - 122404 2015.9

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DOI： 10.1063/1.4931141

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Magnetic Properties and Intrinsic Ferromagnetism in Narrow-gap Ferromagnetic Semiconductor (Ga,Fe)Sb Reviewed

N.T. Tu, P.N. Hai, L.D. Anh, M. Tanaka

Extended Abstracts of the 2015 International Conference on Solid State Devices and Materials 2015.9

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Publisher：The Japan Society of Applied Physics

DOI： 10.7567/ssdm.2015.p-3-4

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Continuous visible-light emission at room temperature in Mn-doped GaAs and Si light-emitting diodes (Presentation Recording) Reviewed

Masaaki Tanaka, Pham Nam Hai, Le Duc Anh

Spintronics VIII 2015.9

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Publisher：SPIE

DOI： 10.1117/12.2191840

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Optical and Magnetic Microstructures in YIG Ferrite Fabricated by Femtosecond Laser Reviewed

Atsushi Ishikawa

Journal of Laser Micro/Nanoengineering 10 ( 1 ) 48 - 52 2015.2

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DOI： 10.2961/jlmn.2015.01.0010

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Growth and characterization of insulating ferromagnetic semiconductor (Al,Fe)Sb Reviewed

Le Duc Anh, Daiki Kaneko, Pham Nam Hai, Masaaki Tanaka

Applied Physics Letters 107 ( 23 ) 232405 - 232405 2015

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DOI： 10.1063/1.4937142

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High-field electroluminescence in semiconductor tunnel junctions with a Mn-doped GaAs layer Reviewed

Pham Nam Hai, Takashi Yatsui, Motoichi Ohtsu, Masaaki Tanaka

Journal of Applied Physics 116 ( 11 ) 113905 - 113905 2014.9

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DOI： 10.1063/1.4895700

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(Ga,Fe)Sb: A p-type ferromagnetic semiconductor Reviewed

Nguyen Thanh Tu, Pham Nam Hai, Le Duc Anh, Masaaki Tanaka

Applied Physics Letters 105 ( 13 ) 132402 - 132402 2014.9

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DOI： 10.1063/1.4896539

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Spin and orbital magnetic moments of Fe in the n-type ferromagnetic semiconductor (In,Fe)As Reviewed

M. Kobayashi, L. D. Anh, P. N. Hai, Y. Takeda, S. Sakamoto, T. Kadono, T. Okane, Y. Saitoh, H. Yamagami, Y. Harada, M. Oshima, M. Tanaka, A. Fujimori

Applied Physics Letters 105 ( 3 ) 032403 - 032403 2014.7

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DOI： 10.1063/1.4890733

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Interplay between strain, quantum confinement, and ferromagnetism in strained ferromagnetic semiconductor (In,Fe)As thin films Reviewed

Daisuke Sasaki, Le Duc Anh, Pham Nam Hai, Masaaki Tanaka

Applied Physics Letters 104 ( 14 ) 142406 - 142406 2014.4

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DOI： 10.1063/1.4870970

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Visible-light electroluminescence in Mn-doped GaAs light-emitting diodes Reviewed

Pham Nam Hai, Daiki Maruo, Masaaki Tanaka

Applied Physics Letters 104 ( 12 ) 122409 - 122409 2014.3

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DOI： 10.1063/1.4869576

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Electronic Excitations of a Magnetic Impurity State in the Diluted Magnetic Semiconductor (Ga,Mn)As Reviewed

M. Kobayashi, H. Niwa, Y. Takeda, A. Fujimori, Y. Senba, H. Ohashi, A. Tanaka, S. Ohya, P. N. Hai, M. Tanaka, Y. Harada, M. Oshima

Physical Review Letters 112 ( 10 ) 2014.3

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DOI： 10.1103/physrevlett.112.107203

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Publishers Note: “Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport” [Appl. Phys. Rev. 1, 011102 (2014)] Reviewed

Masaaki Tanaka, Shinobu Ohya, Pham Nam Hai

Applied Physics Reviews 1 ( 1 ) 019901 - 019901 2014.3

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Publishing type：Research paper (scientific journal) Publisher：{AIP} Publishing

DOI： 10.1063/1.4863688

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Recent progress in III-V based ferromagnetic semiconductors: Band structure, Fermi level, and tunneling transport Reviewed

Masaaki Tanaka, Shinobu Ohya, Pham Nam Hai

Applied Physics Reviews 1 ( 1 ) 011102 - 011102 2014.3

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Language：English Publishing type：Research paper (scientific journal)

DOI： 10.1063/1.4840136

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Epitaxial growth and characterization of n-type magnetic semiconductor (In,Co)As Reviewed

Nguyen Thanh Tu, Le Duc Anh, Pham Nam Hai, Masaaki Tanaka

Japanese Journal of Applied Physics 53 ( 4S ) 04EM05 2014.1

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DOI： 10.7567/jjap.53.04em05

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Three-dimensional nanostructuring in YIG ferrite with femtosecond laser Reviewed

Tomohiro Amemiya, Atsushi Ishikawa, Yuya Shoji, Pham Nam Hai, Masaaki Tanaka, Tetsuya Mizumoto, Takuo Tanaka, Shigehisa Arai

OPTICS LETTERS 39 ( 2 ) 212 - 215 2014.1

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DOI： 10.1364/OL.39.000212

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Control of ferromagnetism by manipulating the carrier wavefunction in ferromagnetic semiconductor (In,Fe)As quantum wells Reviewed

Le Duc Anh, Pham Nam Hai, Masaaki Tanaka

APPLIED PHYSICS LETTERS 104 ( 4 ) 2014.1

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DOI： 10.1063/1.4863214

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Three-dimensional nanostructuring in YIG ferrite with femtosecond laser. Reviewed

Amemiya T, Ishikawa A, Shoji Y, Hai PN, Tanaka M, Mizumoto T, Tanaka T, Arai S

Optics letters 39 ( 2 ) 212 - 215 2014.1

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DOI： 10.1364/ol.39.000212

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Three-dimensional nanostructuring in YIG ferrite with femtosecond laser

Tomohiro Amemiya, Atsushi Ishikawa, Yuya Shoji, Pham Nam Hai, Masaaki Tanaka, Tetsuya Mizumoto, Takuo Tanaka, Shigehisa Arai

Optics InfoBase Conference Papers 2014

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DOI： 10.1364/cleo_si.2014.sth1j.5

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Three-dimensional Nanostructuring in YIG Ferrite with Femtosecond Laser Reviewed

Tomohiro Amemiya, Atsushi Ishikawa, Yuya Shoji, Pham Nam Hai, Masaaki Tanaka, Tetsuya Mizumoto, Takuo Tanaka, Shigehisa Arai

2014 CONFERENCE ON LASERS AND ELECTRO-OPTICS (CLEO) 2014

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Epitaxial growth and properties of n-type magnetic semiconductor (In,Co)As Reviewed

T.T. Nguyen, D.A. Le, N.H. Pham, M. Tanaka

Extended Abstracts of the 2013 International Conference on Solid State Devices and Materials 2013

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DOI： 10.7567/ssdm.2013.ps-12-13

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Effects of laser irradiation on the self-assembly of MnAs nanoparticles in a GaAs matrix Reviewed

Pham Nam Hai, Wataru Nomura, Takashi Yatsui, Motoichi Ohtsu, Masaaki Tanaka

Applied Physics Letters 101 ( 19 ) 193102 - 193102 2012.11

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DOI： 10.1063/1.4765355

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Growth and characterization of n-type electron-induced ferromagnetic semiconductor (In,Fe)As Reviewed

Pham Nam Hai, Le Duc Anh, Shyam Mohan, Tsuyoshi Tamegai, Masaya Kodzuka, Tadakatsu Ohkubo, Kazuhiro Hono, Masaaki Tanaka

Applied Physics Letters 101 ( 18 ) 182403 - 182403 2012.10

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DOI： 10.1063/1.4764947

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Crystalline anisotropic magnetoresistance with two-fold and eight-fold symmetry in (In,Fe)As ferromagnetic semiconductor Reviewed

Pham Nam Hai, Daisuke Sasaki, Le Duc Anh, Masaaki Tanaka

Applied Physics Letters 100 ( 26 ) 262409 - 262409 2012.6

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DOI： 10.1063/1.4730955

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Magnetoresistance enhanced by inelastic cotunneling in a ferromagnetic MnAs nanoparticle sandwiched by nonmagnetic electrodes Reviewed

Ryota Akiyama, Shinobu Ohya, Pham Nam Hai, Masaaki Tanaka

Journal of Applied Physics 111 ( 6 ) 063716 - 063716 2012.3

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DOI： 10.1063/1.3695990

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Electron effective mass in n-type electron-induced ferromagnetic semiconductor (In,Fe)As: Evidence of conduction band transport Reviewed

Pham Nam Hai, Le Duc Anh, Masaaki Tanaka

Applied Physics Letters 101 ( 25 ) 252410 - 252410 2012

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DOI： 10.1063/1.4772630

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Spintronics Materials and Devices - Ferromagnetic Semiconductors and Heterostructures Reviewed

Masaaki Tanaka, Shinobu Ohya, Pham Nam Hai, Ryosho Nakane

2012 CONFERENCE ON OPTOELECTRONIC AND MICROELECTRONIC MATERIALS AND DEVICES (COMMAD 2012) 119 - 120 2012

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DOI： 10.1109/COMMAD.2012.6472389

DOI： 10.1109/commad.2012.6472389

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Structural and magnetic properties of Ge1−xMnx thin films grown on Ge (001) substrates Reviewed

Shinsuke Yada, Pham Nam Hai, Satoshi Sugahara, Masaaki Tanaka

Journal of Applied Physics 110 ( 7 ) 073903 - 073903 2011.10

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DOI： 10.1063/1.3638701

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Phase decomposition diagram of magnetic alloy semiconductor Reviewed

Pham Nam Hai, Shinsuke Yada, Masaaki Tanaka

Journal of Applied Physics 109 ( 7 ) 073919 - 073919 2011.4

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DOI： 10.1063/1.3567112

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Long spin-relaxation time in a single metal nanoparticle. Reviewed

Hai PN, Ohya S, Tanaka M

Nature nanotechnology 5 ( 8 ) 593 - 596 2010.8

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DOI： 10.1038/nnano.2010.130

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Valence-band structure of the ferromagnetic semiconductor GaMnAs studied by spin-dependent resonant tunneling spectroscopy.

Shinobu Ohya, Iriya Muneta, Pham Nam Hai, Masaaki Tanaka

Phys. Rev. Lett. 104 ( 16 ) 167204 - 167204 2010.4

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The valence-band structure and the Fermi level (E(F)) position of ferromagnetic-semiconductor GaMnAs are quantitatively investigated by electrically detecting the resonant tunneling levels of a GaMnAs quantum well (QW) in double-barrier heterostructures. The resonant level from the heavy-hole first state is clearly observed in the metallic GaMnAs QW, indicating that holes have a high coherency and that E(F) exists in the band gap. Clear enhancement of tunnel magnetoresistance induced by resonant tunneling is demonstrated in these double-barrier heterostructures.

DOI： 10.1103/PhysRevLett.104.167204

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Valence-Band Structure of the Ferromagnetic Semiconductor GaMnAs Studied by Spin-Dependent Resonant Tunneling Spectroscopy Reviewed

Shinobu Ohya, Iriya Muneta, Pham Nam Hai, Masaaki Tanaka

Physical Review Letters 104 ( 16 ) 2010.4

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DOI： 10.1103/physrevlett.104.167204

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Electromotive force and huge magnetoresistance in magnetic tunnel junctions Reviewed

Pham Nam Hai, Shinobu Ohya, Masaaki Tanaka, Stewart E. Barnes, Sadamichi Maekawa

Nature 458 ( 7237 ) 489 - 492 2009.3

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DOI： 10.1038/nature07879

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GaMnAs-based magnetic tunnel junctions with an AlMnAs barrier Reviewed

Shinobu Ohya, Iriya Muneta, Pham Nam Hai, Masaaki Tanaka

Applied Physics Letters 95 ( 24 ) 242503 - 242503 2009

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DOI： 10.1063/1.3254218

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Spin-valve effect by ballistic transport in ferromagnetic metal (MnAs)/semiconductor (GaAs) hybrid heterostructures Reviewed

Pham Nam Hai, Yusuke Sakata, Masafumi Yokoyama, Shinobu Ohya, Masaaki Tanaka

PHYSICAL REVIEW B 77 ( 21 ) 2008.6

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DOI： 10.1103/PhysRevB.77.214435

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Spin-valve effect by ballistic transport in ferromagnetic metal (MnAs)/semiconductor (GaAs) hybrid heterostructures Reviewed

Pham Nam Hai, Yusuke Sakata, Masafumi Yokoyama, Shinobu Ohya, Masaaki Tanaka

Physical Review B 77 ( 21 ) 2008.6

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DOI： 10.1103/physrevb.77.214435

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Nature of Magnetic Coupling between Mn Ions in As-GrownGa1−xMnxAsStudied by X-Ray Magnetic Circular Dichroism Reviewed

Y. Takeda, M. Kobayashi, T. Okane, T. Ohkochi, J. Okamoto, Y. Saitoh, K. Kobayashi, H. Yamagami, A. Fujimori, A. Tanaka, J. Okabayashi, M. Oshima, S. Ohya, P. N. Hai, M. Tanaka

Physical Review Letters 100 ( 24 ) 2008.6

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DOI： 10.1103/physrevlett.100.247202

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Properties and Functionalities of MnAs/III-V Hybrid and Composite Structures Reviewed

Masaaki Tanaka, Masafumi Yokoyama, Pham Nam Hai, Shinobu Ohya

SPINTRONICS 82 455 - 485 2008

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DOI： 10.1016/S0080-8784(08)00011-2

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Reconfigurable Logic Gates Using Single-Electron Spin Transistors Reviewed

Pham Nam Hai, Satoshi Sugahara, Masaaki Tanaka

Japanese Journal of Applied Physics 46 ( 10A ) 6579 - 6585 2007.10

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DOI： 10.1143/jjap.46.6579

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154-μm TM-mode waveguide optical isolator based on the nonreciprocal-loss phenomenon: device design to reduce insertion loss Reviewed

T. Amemiya, H. Shimizu, M. Yokoyama, P. N. Hai, M. Tanaka, Y. Nakano

Applied Optics 46 ( 23 ) 5784 - 5784 2007.8

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DOI： 10.1364/ao.46.005784

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1.54-mu m TM-mode waveguide optical isolator based on the nonreciprocal-loss phenomenon: device design to reduce insertion loss Reviewed

T. Amemiya, H. Shimizu, M. Yokoyama, P. N. Hai, M. Tanaka, Y. Nakano

APPLIED OPTICS 46 ( 23 ) 5784 - 5791 2007.8

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Quantum size effect and tunneling magnetoresistance in ferromagnetic-semiconductor quantum heterostructures Reviewed

Shinobu Ohya, Pham Nam Hai, Yosuke Mizuno, Masaaki Tanaka

Physical Review B 75 ( 15 ) 2007.4

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DOI： 10.1103/physrevb.75.155328

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Quantum size effect and tunneling magnetoresistance in ferromagnetic-semiconductor quantum heterostructures Reviewed

Shinobu Ohya, Pham Nam Hai, Yosuke Mizuno, Masaaki Tanaka

PHYSICAL REVIEW B 75 ( 15 ) 2007.4

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DOI： 10.1103/PhysRevB.75.155328

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Spin-dependent transport properties in GaMnAs-based spin hot-carrier transistors Reviewed

Yosuke Mizuno, Shinobu Ohya, Pham Nam Hai, Masaaki Tanaka

Applied Physics Letters 90 ( 16 ) 162505 - 162505 2007.4

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DOI： 10.1063/1.2724771

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Magnetic properties of MnAs nanoclusters embedded in a GaAs semiconductor matrix Reviewed

Pham Nam Hai, Keisuke Takahashi, Masafumi Yokoyama, Shinobu Ohya, Masaaki Tanaka

Journal of Magnetism and Magnetic Materials 310 ( 2 ) 1932 - 1934 2007.3

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DOI： 10.1016/j.jmmm.2006.10.766

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Nonreciprocal propagation of light without external magnetic fields in a semiconductor waveguide isolator with a MnAs layer Reviewed

T. Amemiya, H. Shimizu, P.N. Hai, M. Tanaka, Y. Nakano

Journal of Magnetism and Magnetic Materials 310 ( 2 ) 2161 - 2163 2007.3

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DOI： 10.1016/j.jmmm.2006.11.039

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Waveguide-Based 1.5 µm Optical Isolator Based on Magneto-Optic Effect in Ferromagnetic MnAs Reviewed

Tomohiro Amemiya, Hiromasa Shimizu, Pham Nam Hai, Masafumi Yokoyama, Masaaki Tanaka, Yoshiaki Nakano

Japanese Journal of Applied Physics 46 ( 1 ) 205 - 210 2007.1

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DOI： 10.1143/jjap.46.205

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Single mode operation of 1.5 mu m TM-mode waveguide optical isolators based on the nonreciprocal-loss phenomenon Reviewed

T. Amemiya, H. Shimizu, M. Yokoyama, P. N. Hai, M. Tanaka, Y. Nakano

2007 CONFERENCE ON LASERS & ELECTRO-OPTICS/QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (CLEO/QELS 2007), VOLS 1-5 528 - + 2007

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Language：English Publishing type：Research paper (international conference proceedings)

DOI： 10.1109/CLEO.2007.4452994

DOI： 10.1109/cleo.2007.4452994

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Semiconductor waveguide optical isolator based on nonreciprocal loss induced by ferromagnetic MnAs Reviewed

T. Amemiya, H. Shimizu, Y. Nakano, P. N. Hai, M. Yokoyama, M. Tanaka

Applied Physics Letters 89 ( 2 ) 021104 - 021104 2006.7

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DOI： 10.1063/1.2220016

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Spin polarized tunneling in III–V-based heterostructures with a ferromagnetic MnAs thin film and GaAs:MnAs nanoclusters Reviewed

Pham Nam Hai, Masafumi Yokoyama, Shinobu Ohya, Masaaki Tanaka

Physica E: Low-dimensional Systems and Nanostructures 32 ( 1-2 ) 416 - 418 2006.5

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DOI： 10.1016/j.physe.2005.12.082

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TM mode optical waveguide isolator with 8.8 dB/mm nonreciprocal propagation induced by ferromagnetic MnAs Reviewed

T. Amemiya, H. Shimizu, Y. Nakano, P. N. Hai, M. Yokoyama, M. Tanaka

2006 OPTICAL FIBER COMMUNICATION CONFERENCE/NATIONAL FIBER OPTIC ENGINEERS CONFERENCE, VOLS 1-6 2310 - + 2006

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DOI： 10.1109/ofc.2006.215931

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Tunneling magnetoresistance of MnAs thin film/GaAs∕AlAs∕GaAs:MnAs nanoclusters and its AlAs barrier thickness dependence Reviewed

Pham Nam Hai, Masafumi Yokoyama, Shinobu Ohya, Masaaki Tanaka

Applied Physics Letters 89 ( 24 ) 242106 - 242106 2006

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DOI： 10.1063/1.2405399

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Resonant tunneling effect and tunneling magnetoresistance in GaMnAs quantum-well double-barrier heterostructures Reviewed

S. Ohya, P. N. Hai, Y. Mizuno, M. Tanaka

PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 3, NO 12 3 ( 12 ) 4184 - 4187 2006

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Resonant tunneling effect and tunneling magnetoresistance in GaMnAs quantum-well double-barrier heterostructures Reviewed

S. Ohya, P. N. Hai, Y. Mizuno, M. Tanaka

physica status solidi (c) 3 ( 12 ) 4184 - 4187 2006

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Publishing type：Research paper (scientific journal) Publisher：Wiley

DOI： 10.1002/pssc.200672882

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Tunneling magnetoresistance in GaMnAs∕AlAs∕InGaAs∕AlAs∕GaMnAs double-barrier magnetic tunnel junctions Reviewed

Shinobu Ohya, Pham Nam Hai, Masaaki Tanaka

Applied Physics Letters 87 ( 1 ) 012105 - 012105 2005.7

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DOI： 10.1063/1.1978976

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強磁性半導体ルネサンス : Fe添加Ⅲ-Ⅴ族強磁性半導体がもたらす新展開

レデゥックアイン, グエンタントゥ, 瀧口耕介, 小林正起, ファムナムハイ, 田中雅明

固体物理 / アグネ技術センター [編] 58 ( 2 ) 67 - 80 2023.2

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招待講演 Co/Tb磁性細線における磁区の記録・駆動とトポロジカル絶縁体の適用—Invited Talk : Recording and Driving of Magnetic Domains in [Co/Tb] Magnetic Nanowires and Application of Topological Insulator

宮本泰敬, 加藤大典, 髙橋真央, 小倉渓, 井口義則, ファムナムハイ

映像情報メディア学会技術報告 = ITE technical report 46 ( 40 ) 17 - 22 2022.12

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Evaluation of Spin Hall effect in YPt alloy

Fujiwara Kou, Shirokura Takanori, Nam Hai Pham

JSAP Annual Meetings Extended Abstracts 2021.1 1701 - 1701 2021.2

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DOI： 10.11470/jsapmeeting.2021.1.0_1701

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Sb concentration dependence of spin Hall effect in BiSb topological insulator

市村雅貴, NGUYEN Huynh Duy Khang, 高橋真央, 宮本泰敬, PHAM Nam Hai

応用物理学会秋季学術講演会講演予稿集(CD-ROM) 82nd 2021

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Improvement of output in anomalous Hall effect sensors using (In,Fe)Sb

Takahashi Shunsuke, Ekaputra Yohar Kevin, Tanaka Masaaki, Pham Nam Hai

JSAP Annual Meetings Extended Abstracts 2020.1 1961 - 1961 2020.2

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DOI： 10.11470/jsapmeeting.2020.1.0_1961

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Improved thermal stability of BiSb pure spin current source for embedded MRAM

NAKANO SOICHIRO, Kenichiro Yao, NamHai Pham

JSAP Annual Meetings Extended Abstracts 2020.1 1942 - 1942 2020.2

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DOI： 10.11470/jsapmeeting.2020.1.0_1942

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Fabrication of Integrated Writer & Reduction of Writer Current in Magnetic Nanowire Memory

宮本泰敬, 宮本泰敬, 堀洋祐, 遠藤充泰, PHAM Nam Hai, PHAM Nam Hai, 石井紀彦

電子情報通信学会大会講演論文集(CD-ROM) 2020 2020

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N-type and p-type ferromagnetic semiconductors: High Curie temperature and heterostructure devices

Anh Le Duc, Nguyen Thanh Tu, Takiguchi Kosuke, Nam Hai Pham, Tanaka Masaaki

JSAP Annual Meetings Extended Abstracts 2019.2 121 - 121 2019.9

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DOI： 10.11470/jsapmeeting.2019.2.0_121

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Ultrahigh performance pure spin current source using BiSb topological insulator

Hai PHAM Nam, Khang Nguyen Huynh Duy, Shirokura Takanori, Yao Kenichiro

JSAP Annual Meetings Extended Abstracts 2019.2 128 - 128 2019.9

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DOI： 10.11470/jsapmeeting.2019.2.0_128

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Large spin-valve effect in a lateral spin-valve device with MnGa electrodes

Chonan Koki, Duy Khang Nguyen Huynh, Tanaka Masaaki, Nam Hai Pham

JSAP Annual Meetings Extended Abstracts 2019.1 2021 - 2021 2019.2

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DOI： 10.11470/jsapmeeting.2019.1.0_2021

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Fabrication and evaluation of lateral spin-valve devices using MnAs spin injector

Yamane Keita, Yao Kenichiro, Tanaka Masaaki, Nam Hai Pham

JSAP Annual Meetings Extended Abstracts 2019.1 2020 - 2020 2019.2

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DOI： 10.11470/jsapmeeting.2019.1.0_2020

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トポロジカル絶縁体スピントロニクス—Topological Insulator Spintronics—スピントロニクスの最前線

ファムナムハイ

応用電子物性分科会誌 = Bulletin of solid state physics and applications / 応用物理学会応用電子物性分科会編 25 ( 5 ) 173 - 178 2019

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Fe-doped ferromagnetic semiconductors and their device applications

PHAM Nam Hai, LE Duc Anh, NGUYEN Thanh Tu, TANAKA Masaaki

Oyo Buturi 87 ( 10 ) 754 - 758 2018.10

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We review recent studies of a new class of Fe-doped III-V ferromagnetic semiconductors (FMS). We first briefly summarize the history of FMS studies, and point out the unsolved problems of the most intensively studied Mn-doped III-V FMSs such as (GaMn)As. We then discuss the possibility and prospects of using Fe as a magnetic impurity in narrow-gap III-V semiconductors to realize a new family of FMSs that can solve all the problems of Mn-doped FMSs. We describe the crystal growth, detailed structural characterizations, and fundamental magnetic properties of n-type (InFe)As, p-type (GaFe)Sb, and n-type (InFe)Sb. We discuss possible applications of these Fe-doped FMSs to semiconductor spin devices.

DOI： 10.11470/oubutsu.87.10_754

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Other Link： https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16H02095/
Crystal Growth of BiSb topological insulator on GaAs(001), (111)A and (111)B substrates

Yao Kenichiro, Nguyen Huynh Duy Khang, Ichimura Masataka, Pham Nam Hai

JSAP Annual Meetings Extended Abstracts 2018.2 2146 - 2146 2018.9

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DOI： 10.11470/jsapmeeting.2018.2.0_2146

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Fabrication and evaluation of Fe delta-doped (In,Fe)Sb high sensitivity magnetic sensors

Nishijima Kento, Tanaka Masaaki, Pham Nam Hai

JSAP Annual Meetings Extended Abstracts 2018.2 2148 - 2148 2018.9

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DOI： 10.11470/jsapmeeting.2018.2.0_2148

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Spin dependent transport characteristics of spin bipolar transistors based on Fe doped ferromagnetic semiconductors

Chonan Koki, Arakawa Yuto, Tanaka Masaaki, Nam Hai Pham

JSAP Annual Meetings Extended Abstracts 2018.2 2149 - 2149 2018.9

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DOI： 10.11470/jsapmeeting.2018.2.0_2149

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Electrical properties of Bi_1-xSb_x spin Hall thin films grown on GaAs(111)A substrates

Yao Kenichiro, Ueda Yugo, Huynh Duy Khang Nguyen, Nam Hai Pham

JSAP Annual Meetings Extended Abstracts 2017.1 2166 - 2166 2017.3

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DOI： 10.11470/jsapmeeting.2017.1.0_2166

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Bias and temperature dependence of giant magnetoresistance in (In,Fe)As/(Ga,Fe)Sb spin diode

Otsuka Tomohiro, Arakawa Yuto, Nishijima Kento, Tanaka Masaaki, Pham NamHai

JSAP Annual Meetings Extended Abstracts 2017.1 2172 - 2172 2017.3

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DOI： 10.11470/jsapmeeting.2017.1.0_2172

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Giant spin dependent transport characteristics in Fe-doped ferromagnetic semiconductor p-n junctions

Arakawa Yuto, Otsuka Tomohiro, Tanaka Masaaki, Nam Hai Pham

JSAP Annual Meetings Extended Abstracts 2016.2 2015 - 2015 2016.9

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DOI： 10.11470/jsapmeeting.2016.2.0_2015

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International students from Vietnam: Past, present and future

PHAM Nam Hai

Oyo Buturi 85 ( 3 ) 234 - 235 2016.3

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DOI： 10.11470/oubutsu.85.3_234

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Magnetic properties of (In,Fe)As grown on vicinal GaAs substrates

Nagamine Akihide, Yoshida Munehiko, Tanaka Masaaki, Hai Pham Nam

JSAP Annual Meetings Extended Abstracts 2016.1 2083 - 2083 2016.3

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DOI： 10.11470/jsapmeeting.2016.1.0_2083

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Epitaxial growth of Bi_1-xSb_x spin-Hall alloy on GaAs(111) substrates

Ueda Yugo, Nam Hai Pham

JSAP Annual Meetings Extended Abstracts 2016.1 1986 - 1986 2016.3

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DOI： 10.11470/jsapmeeting.2016.1.0_1986

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Magneto-optical integrated circuits by femtosecond laser modeling in YIG

Amemiya Tomohiro, Gu Zhichen, Ishikawa Atsushi, Shoji Yuya, Nam Hai Pham, Tanaka Masaaki, Mizumoto Tetsuya, Tanaka Takuo, Arai Shigehisa

JSAP Annual Meetings Extended Abstracts 2015.1 1077 - 1077 2015.2

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DOI： 10.11470/jsapmeeting.2015.1.0_1077

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強磁性半導体(In,Fe)As:Beの磁化過程のXMCDによる研究

坂本祥哉, LE Duc Anh, PHAM Nam Hai, 芝田悟朗, 高橋文雄, 小林正起, 竹田幸治, 山上浩志, 山上浩志, 斎藤祐児, 小出常晴, 田中雅明, 藤森淳

物構研サイエンスフェスタ要旨集 2013 2014

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Comment on "Reconciling results of tunnelling experiments on (Ga,Mn)As" arXiv:1102.3267 by Dietl and Sztenkiel

Shinobu Ohya, Kenta Takata, Iriya Muneta, Pham Nam Hai, Masaaki Tanaka

(comment paper in arXiv) 2011.2

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軟X線磁気円二色性による希薄磁性半導体Ga_1-xMn_xAsの熱処理前後におけるスピン電子状態変化の研究

竹田幸治, 岡根哲夫, 藤森淳, 斎藤祐児, 山上浩志, 山上浩志, 大矢忍, HAI P. N., 田中雅明

日本物理学会講演概要集 66 ( 1 ) 2011

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スピンバッテリーにおける起電力の素子構造依存特性

秋山了太, HAI Pham Nam, 田中雅明

応用物理学関係連合講演会講演予稿集(CD-ROM) 57th 2010

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Spin-dependent resonant tunneling effect in ferromagnetic-semiconductor quantum heterostructures

OHYA S., HAI P. N., TANAKA M.

Bulletin of Topical Symposium of the Magnetics Society of Japan 159 25 - 29 2008.3

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CiNii Books

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非相反損失による導波路光アイソレータの低損失化および単一モード伝搬の確認

雨宮智宏, 雨宮智宏, 清水大雅, 清水大雅, 横山正史, 横山正史, HAI P. N., HAI P. N., 田中雅明, 田中雅明, 中野義昭, 中野義昭

応用物理学関係連合講演会講演予稿集 54th ( 3 ) 2007

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TM mode waveguide optical isolator based on the nonreciprocal loss induced by ferromagnetic MnAs

AMEMIYA Tomohiro, SHIMIZU Hiromasa, Hai P. N, YOKOYAMA Masafumi, TANAKA Masaaki, NAKANO Yoshiaki

Technical report of IEICE. OPE 106 ( 435 ) 19 - 22 2006.12

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Language：Japanese Publisher：一般社団法人電子情報通信学会

Waveguide optical isolator for 1.5μm TM mode was developed. The device consists of an InGaAlAs/InP semiconductor optical amplifier covered with a ferromagnetic MnAs layer. The combination of the optical waveguide and the magnetized ferromagnetic metal layer produces a magneto-optic effect called the nonreciprocal loss-a phenomenon where the propagation loss of light is larger in backward than in forward propagation. Based on this phenomenon, we fabricated a ridge waveguide device and obtained its single-mode operation with a small insertion loss (〜10dB). The device showed a stable isolation performance of 7.2 dB/mm from 1.53μm to 1.55μm.

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強磁性MnAsによる非相反損失を用いた導波路型光アイソレータのゼロ磁場動作

AMEMIYA TOMOHIRO, SHIMIZU HIROMASA, HAI P. N, TANAKA MASAAKI, NAKANO YOSHIAKI

応用物理学会学術講演会講演予稿集 67th ( 3 ) 1095 2006.8

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エピタキシャル強磁性電極MnAsを用いた非相反損失変化による導波路型光アイソレータ

AMEMIYA TOMOHIRO, SHIMIZU HIROMASA, HAI P. N, YOKOYAMA MASAFUMI, TANAKA MASAAKI, NAKANO YOSHIAKI

応用物理学関係連合講演会講演予稿集 53rd ( 3 ) 1265 2006.3

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J-GLOBAL

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CS-8-10 Integratable Waveguide Optical Isolators Based on the Nonreciprocal Loss Shift

Shimizu Hiromasa, Amemiya Tomohiro, Hai Pham Nam, Yokoyama Masafumi, Tanaka Masaaki, Nakano Yoshiaki

Proceedings of the Society Conference of IEICE 2005 ( 1 ) "S - 87"-"S-88" 2005.9

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CiNii Research

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24aPS-24 Magnetic field dependence of XMCD of GaMnAs II

Takeda Yukiharu, Okamoto Jun, Okane Tetsuo, Fujimori Shin-ichi, Saitoh Yuji, Muramatu Yasuji, Fujimori Atushi, Okabayashi Jun, Oshima Masaharu, Oya Shinobu, Pham Nam Hai, Tanaka Masaaki

Meeting abstracts of the Physical Society of Japan 60 ( 1 ) 663 - 663 2005.3

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TM mode nonreciprocal loss shift type waveguide optical isolator using epitaxial MnAs as a ferromagnetic electrode

雨宮智宏, 雨宮智宏, 雨宮智宏, 清水大雅, 清水大雅, HAI P. N., HAI P. N., 横山正史, 横山正史, 田中雅明, 田中雅明, 中野義昭, 中野義昭

日本応用磁気学会学術講演概要集 29th (CD-ROM) 2005

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Presentations

Large inverse spin Hall effect in BiSb topological insulator and application to SOT magnetic sensor

H. H. Huy, J. Sasaki, N. H., D. Khang, S. Namba, P. N. Hai

CREST領域会議「トポロジカル材料科学の構築による革新的材料・デバイスの創出」 2024.1

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トポロジカル表面状態を用いるスピン軌道トルク磁気メモリの創製

ファムナムハイ, 宮本泰敬, 小林正起

CREST領域会議「トポロジカル材料科学の構築による革新的材料・デバイスの創出」 2024.1

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Growth and evaluation of BiSb topological insulator ultrathin films on Si(111) substrates for superconductor/2D-TI topological quantum bits

Y. Osada, M. Vaßen-Carl, A. R. Jalil, P. Schüffelgen, P. N. Hai

The 27th Symposium on the Physics and Applications of Spin-related Phenomena in Semiconductors (PASPS-27) 2024.3

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トポロジカル絶縁体BiSbを適用した磁性細線メモリー

宮本泰敬, 加藤大典, 小倉渓, 木下延博, Pham Nam Hai

CREST領域会議「トポロジカル材料科学の構築による革新的材料・デバイスの創出」 2024.1

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Electronic Structure Study of Heterointerface between Topological Insulator and Ferromagnet by Angle-Resolve Photoemission Spectroscopy

M. Kobayashi, K. Inagaki, P. N. Hai

CREST領域会議「トポロジカル材料科学の構築による革新的材料・デバイスの創出」 2024.1

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Giant spin Hall effect in sputtered topological semimetal YPtBi films grown at low temperature

Takanori Shirokura, Pham Nam Hai

The 71th JSAP Spring Meeting 2024 2024.3

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Large inverse spin Hall effect in BiSb topological insulator for beyond 4 TB/In2 magnetic recording technology

H. H. Huy, J. Sasaki, N. H., D. Khang, S. Namba, P. N. Hai, Q. Le, B. York, C. Hwang, X. Liu, M. Gribelyuk, X. Xu, S. Le, M. Ho, H. Takano

IEEE Magnetics Society Summer School 2024 2024.6

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Observation of impurity band in (InFe)(SbBi) ferromagnetic semiconductor using infrared magnetic circular dichroism spectroscopy

Kota Ejiri, Yota Endo, Kenta Takabayasi, Masaaki Tanaka, Pham Nam Hai

The 71th JSAP Spring Meeting 2024 2024.3

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トポロジカル絶縁体BiSbのテラヘルツ分光特性

西山黎, ファムナムハイ, 橋谷田俊, 河野行雄

第71回応用物理学会春季学術講演会 2024.3

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High spin Hall angle in BiSb topological insulator and perpendicularly magnetized CoFeB/MgO multilayers with metallic interfacial layers

Ruixian Zhang, Ho Hoang Huy, Takanori Shirokura, Pham Nam Hai, Quang Le, Brian R. York, Cherngye Hwang, Xiaoyong Liu, Xiaoyu Xu, Son Le, Michael Gribelyuk, Hisashi Takano, Maki Maeda, Fan Tuo, Yu Tao

The 71th JSAP Spring Meeting 2024 2024.3

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High spin Hall performance in YPtBi topological semimetal and perpendicular-anisotropy CoFeB junctions

Reo Yamamoto, Takanori Shirokura, Pham Nam Hai

The 71th JSAP Spring Meeting 2024 2024.3

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Interface Topological States in a Bi/MnGa Heterostructure

M. Kobayashi, N. H., D. Khang, T. Takeda, K. Araki, R. Okano, M. Suzuki, K. Kuroda, K. Yaji, K. Sugawara, S. Souma, K. Nakayama, M. Kitamura, K. Horiba, A. Fujimori, T. Sato, S. Shin, M. Tanaka, Pham Nam Hai

Symposium of the Spintronics Research Network of Japan (Spin-RNJ 2023) 2024.3

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(Keynote) A new class of Fe-doped III-V ferromagnetic semiconductors with high Curie temperature and their quantum heterostructures Invited

Masaaki Tanaka, Kosuke Takiguchi, Nguyen Thanh Tu, Le Duc Anh, Pham Nam Hai

The 5th International Symposium on Advanced Magnetic Materials and Applications (ISAMMA2024) 2024.8

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High spin Hall angle in heterostructures of BiSb topological insulator and perpendicularly magnetized CoFeB/MgO multilayers with metallic interfacial layers

Z. Ruixian, H. H. Huy, Q. Le, B. York, C. Hwang, X. Liu, M. Gribelyuk, X. Xu, S. Le, M. Maeda, F. Tuo, Y. Tao, H. Takano, T. Shirokura, P. N. Hai

The 22nd International Conference on Magnetism (ICM2024) 2024.6

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(Invited) A new class of Fe-doped III-V ferromagnetic semiconductors with high Curie temperatures and their quantum heterostructures Invited

Masaaki Tanaka, Kosuke Takiguchi, Nguyen Thanh Tu, Le Duc Anh, Pham Nam Hai

36th International Conference on the Physics of Semiconductors (ICPS) 2024 2024.7

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三次元磁性細線メモリに向けた異常ホール効果を用いた微細磁性細線における磁壁移動の電気的な評価

加々美尚, Pham Nam Hai

第23回スピントロニクス入門セミナー若手スピントロニクスワークショップ 2024.10

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Growth and evaluation of highly textured BiSb(001) topological insulator on Si/SiOx

L. Wentao, H. H. Huy, S. Takahashi, Y. Hirayama, Y. Kato, P. N. Hai

The 85th JSAP Autumn Meeting 2024 2024.9

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Spin Hall effect in annealed BiSb topological thin films deposited on Si/SiOx substrates

H. H. Huy, L. Wentao, S. Takahashi, Y. Hirayama, Y. Kato, P. N. Hai

The 85th JSAP Autumn Meeting 2024 2024.9

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New method for suppression of magnetic domain wall shift error in 3D magnetic domain-wall memory

Pham Nam Hai, Takanori Shirokura, Nguyen Huynh Duy Khang

SSDM 2024 2024.9

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Very high Curie temperature (530 K) in (Ga,Fe)Sb ferromagnetic semiconductor grown by step-flow mode on vicinal GaAs substrates

Pham Nam Hai, Ken Takabayashi, Kota Ejiri, Masaaki Tanaka

The 23rd International Conference on Molecular-Beam Epitaxy (ICMBE2024) 2024.9

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(Invited) Topological materials for advanced magnetic memory and sensor Invited

Pham Nam Hai

The 5th International Symposium on Advanced Magnetic Materials and Applications (ISAMMA2024) 2024.8

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Detection of Fe-induced impurity band in Bi-doped (InFe)(SbBi) ferromagnetic semiconductor using infrared magnetic circular dichroism spectroscopy

Kota Ejiri, Yota Endo, Kenta Takabayashi, Masaaki Tanaka, Pham Nam Hai

The 5th International Symposium on Advanced Magnetic Materials and Applications (ISAMMA2024) 2024.8

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Industrial property rights

磁気センサ

PHAMNAM HAI, 白倉孝典, 近藤剛

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Applicant：国立大学法人東京科学大学, キオクシア株式会社

Application no：特願2024-195845 Date applied：2024.11

Announcement no：特開2025-013618 Date announced：2025.1

Rights holder：国立大学法人東京科学大学, キオクシア株式会社

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スピン軌道トルク層とハイブリッドした非局在スピンバルブ読み取りセンサ

PHAMNAM HAI, クアンレイ, リウシャオユン, ブライアンアールヨーク, チャーニーファン, ソンティーレイ, 高野公史, トゥオファン, ハッサンオスマン

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Applicant：国立大学法人東京科学大学, Western Digital Technologies, Inc.

Application no：特願2024-097247 Date applied：2024.6

Announcement no：特開2025-003937 Date announced：2025.1

Rights holder：国立大学法人東京科学大学, Western Digital Technologies, Inc.

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スピン軌道－スピン軌道ロジック

PHAMNAM HAI, クアンレイ, リウシャオユン, ブライアンアールヨーク, チャーニーファン, 高野公史

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Application no：特願2024-097248 Date applied：2024.6

Announcement no：特開2025-003938 Date announced：2025.1

Rights holder：国立大学法人東京科学大学, Western Digital Technologies, Inc.

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トポロジカル絶縁体材料による局所的および非局所的スピン軌道トルク（ＳＯＴ）書き込みヘッド

PHAMNAM HAI, クアンレイ, リウシャオユン, ブライアンアールヨーク, チャーニーファン, 高野公史, ハッサンオスマン, ソンティーレイ, シャロンバイン, 前田麻貴, トゥオファン, ユタオ

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Applicant：国立大学法人東京科学大学, Western Digital Technologies, Inc.

Application no：特願2024-096188 Date applied：2024.6

Announcement no：特開2025-003936 Date announced：2025.1

Rights holder：国立大学法人東京科学大学, Western Digital Technologies, Inc.

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磁気メモリ及びその製造方法

PHAMNAM HAI, グエンフィンズィカン, 白倉孝典

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Applicant：国立大学法人東京工業大学.

Application no：特願PCT/JP2024/014471 Date applied：2024.4

Publication no：WO2024/214719 Date published：2024.10

Rights holder：国立大学法人東京科学大学

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磁性細線媒体、磁壁駆動型メモリ、磁壁駆動型空間光変調器および磁性細線媒体の製造方法

PHAMNAM HAI, ゲィンフンユィカン, 高橋真央, 井口義則, 宮本泰敬, 加藤大典, 小倉渓, 中谷真規

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Applicant：国立大学法人東京工業大学, 日本放送協会

Application no：特願2022-115835 Date applied：2022.7

Announcement no：特開2024-013615 Date announced：2024.2

Rights holder：国立大学法人東京工業大学, 日本放送協会

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スピンホール発振器および磁気記録デバイス、計算機.

PHAMNAM HAI, 白倉孝典

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Applicant：国立大学法人東京工業大学

Application no：特願2021-503967 Date applied：2020.2

Publication no：WOWO 2020/179493 Date published：2020.9

Patent/Registration no：特許第7493249号 Date registered：2024.5

Rights holder：国立大学法人東京工業大学

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Awards

Excellent Research Award

2020 The Magnetics Society of Japan

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German Innovation Award “Gottfried Wagener Prize 2019”

2019 German Chamber of Commerce and Industry in Japan

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Marubun Research Encouragement Award

2017 Marubun Reseach Promotion Foundation

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Ando Memorial Academic Award

2013 The foundation of Ando Laboratory

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SSDM Young Researcher Award

2009 International Conference on Solid State Devices and Materials Huge Magnetoresistance Effect in Semiconductor based Nanostructures with Zinc-blende MnAs Nanoparticles

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President Special Award

2009 University of Tokyo Spin dependent transport phenomena in III-V semiconductor heterostructures with ferromagnetic MnAs nano-scale particles

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Dean of School of Engineering Award (Best research Award)

2009 University of Tokyo Spin dependent transport phenomena in III-V semiconductor heterostructures with ferromagnetic MnAs nano-scale particles

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第20回独創性を拓く先端技術大賞最優秀賞 (文部科学大臣賞)

2006 Sankei

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Dean of School of Engineering Award (Research)

2006 University of Tokyo

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EE Department Excellent Master Thesis Award

2006 University of Tokyo

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Inose Academic Research Encouragement Award

2005 電気電子情報学術振興財団

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EE Department Excellent Bachelor Thesis Award

2004 University of Tokyo

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Research Projects

トポロジカル絶縁体を用いる超低消費電力磁気抵抗メモリの創製

Grant number：20F20050 2020.4 - 2022.3

日本学術振興会科学研究費助成事業特別研究員奨励費

PHAM NAM・HAI, NGUYEN KHANG

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Grant amount：\2300000 （ Direct Cost: \2300000 ）

本研究では、スピンホール効果が極めて強いかつ高い電気伝導率を両立できるトポロジカル絶縁体をスピン注入源として使用し、超低電流密度かつ超高速な書き込みができるSOT-MRAMを実証する。トポロジカル絶縁体の巨大なスピンホール効果による磁化反転を実現できれば、MRAMの書き込み電力2桁、書き込み速度1桁、ビット密度1桁が向上でき、従来の揮発性メモリであるSRAMやDRAMを置き換えると期待できる。我々は2021年度の研究では、次の成果を達成した。
1.Si/SiOx基板上にスパッタリング製膜したトポロジカル絶縁体BiSb/Pt/Co/Pt垂直磁化膜を作製し、BiSbの大きなスピンホール角(2.4)および比較的に高い電気伝導率(1.0ｘ10E5 Ohm-1m-1)を実証した。発表論文：Appl. Phys. Lett. 119, 082403, (2021)
2.サファイア基板上にスパッタリング製膜したトポロジカル絶縁体BiSb/(Co/Pt)垂直磁化膜を作製し、BiSbの巨大なスピンホール角(10.7)および高い電気伝導率(1.8ｘ10E5 Ohm-1m-1)を達成した。発表論文：Sci. Rep. 12, 2998 (2022)
3.Si/SiOx基板上にスパッタリング製膜したトポロジカル絶縁体BiSb/(Co/Pt)垂直磁化膜の800 nmサイズの素子を作製し、BiSbによる超高速(1 ns)および超低消費電力(従来より一桁小さい電流密度)の磁反転に成功した。発表論文：Appl. Phys. Lett. 120, 152401 (2022)

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Breaking the performance limit of spin transistors by using quantum transport

Grant number：18H01492 2018.4 - 2021.3

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Pham Nam Hai

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Grant amount：\17420000 （ Direct Cost: \13400000 、 Indirect Cost：\4020000 ）

In this work, we aimed to solve the conductivity mismatch problem at the interface of ferromagnetic metal / semiconductor by utilizing ballistic transport in nanoscale semiconductor channel. We fabricated nanoscale Si-based spin valve devices with Fe/(Mg)/MgO/Ge spin injector/detector and 20 nm-long Si channel, and achieved a large spin-valve ratio of -3.6% and large spin-dependent output voltage of 25 mV. We then fabricated fully epitaxial MnGa/GaAs/MnGa III-V semiconductor-based nanoscale spin valve devices, and achieved a world-record spin valve ratio of 12% and spin-dependent output voltage of 33 mV. Our results demonstrate that ballistic transport in nanoscale semiconductor is very promising for realization of high performance spin transistors.

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Research of pure spin current source using tunable topological insulator

Grant number：16K14228 2016.4 - 2019.3

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

PHAM NAM HAI

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Grant amount：\3770000 （ Direct Cost: \2900000 、 Indirect Cost：\870000 ）

In this research, we developed a high-performance pure spin current source using BiSb topological insulator thin films for the next generation spin-orbit torque (SOT) MRAM. We developed growth techniques for high quality BiSb thin films with both high electrical conductivity and high spin Hall angle. We found that BiSb(012) thin films have a giant spin Hall angle of 52 at room temperature. We further demonstrated current-induced magnetization switching of a MnGa ferromagnetic thin film with a current density as low as 1.5 MA/square cm. This value is one to two orders of magnitudes lower than those of heavy metal/MnGa bilayers. Furthermore, the spin Hall conductivity of BiSb is 30 times higher than that of Pt, and 100 times higher than that of other topological insulators, such as Bi2Se3. Our results show that BiSb is very promising for SOT-MRAM.

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Spin-functional materials and devices using narrow-gap ferromagnetic semiconductors

Grant number：16K14224 2016.4 - 2018.3

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research

Tanaka Masaaki, Le Duc Anh, Nguyen Thanh Tu, Pham Nam Hai

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Grant amount：\3770000 （ Direct Cost: \2900000 、 Indirect Cost：\870000 ）

We have successfully grown a new class of narrow-gap III-V based ferromagnetic semiconductors with zinc-blende crystal structures and their heterostructures. We have revealed their properties and functionalities, which can be applied to spintronics devices. Ferromagnetic semiconductors (FMS) are alloy semiconductors doped with magnetic atoms and have both the properties of semiconductors and ferromagnets, thus expected to be functional materials for next-generation electronics. We have created p-type (Ga,Fe)Sb and n-type (In,Fe)Sb whose Curie temperatures are higher than room temperature, and their quantum heterostructures. These new materials and heterostructures are shown to have unique and useful properties, which can be applied to future spintronics devices.

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強磁性半導体超薄膜におけるスピン依存熱電効果

Grant number：15F15357 2015.11 - 2018.3

日本学術振興会科学研究費助成事業特別研究員奨励費

PHAM NAM・HAI, BUI CONG TINH

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Grant amount：\2300000 （ Direct Cost: \2300000 ）

近年に磁性材料と半導体材料の特長を融合できる新材料として強磁性半導体は大変注目されている。強磁性半導体においては、通常の半導体と異なり、スピンに依存する様々な熱電効果存在する。強磁性半導体におけるスピン依存熱電効果を利用すれば、従来の半導体よりも性能が格段に高い熱電材料が開発でき、高性能な熱電素子に応用できると期待されている。
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そこで、本研究では、常温でも強磁性が発現できる(InFe)Sb鉄系強磁性半導体薄膜を対象にスピン依存熱電効価の評価を行った。MBE法で製膜した(InFe)Sb薄膜に対して、面内スピン依存熱電効果の評価を行った。その結果、熱電の横方向電圧が面内磁化に対して、偶関数の振る舞いを示したことを観測した。また、熱電の横方向電圧の磁化方向の角度依存性および温度依存性を系統的に調べた。その結果、(InFe)Sbの薄膜の面内スピン依存熱電効果がプラナーネルンスト効果によって発生することを確認した。
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観測したプラナーネルンスト効果を理論的に解析するために、面内スピン依存熱伝導と面内スピン依存電気伝導現象の間にモット関係が成り立つことを仮定し、横方向熱電係数Sxyとプレナーホール抵抗率ρxyの関係を定式化した。この関係が成り立つことを証明するために、同じ(InFe)Sbの薄膜に対して、プラナーホール効果の磁化依存性および温度依存性も測定した。得られた横方向熱電係数Sxyとプレナーホール抵抗率ρxyをモット関係から導出した式で定量的に説明可能であることを明らかにした。これにより、面内スピン依存熱伝導と面内スピン依存電気伝導現象の間にモット関係が成り立つことを世界で初めて成功した。以上の研究成果が鉄系強磁性半導体のスピン依存熱電現象の評価技術や初期なデータとして貴重であり、今後の鉄系強磁性半導体のスピン依存熱電デバイスに貢献できる。

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Research on semiconductor spin devices with ferromagnetic semiconductors

Grant number：15H03988 2015.4 - 2018.3

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

PHAM NAM HAI

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Grant amount：\16900000 （ Direct Cost: \13000000 、 Indirect Cost：\3900000 ）

In this research, we successfully developed a new Fe-doped p-type ferromagnetic semiconductor (Ga,Fe)Sb and a new n-type ferromagnetic semiconductor (In,Fe)Sb, which are necessary for fabrication of semiconductor spin devices. Furthermore, we demonstrated intrinsic ferromagnetism in both materials at room-temperature. Using Fe-doped ferromagnetic semiconductors, we fabricated spin diodes and spin transistors, and investigated their spin-dependent transport characteristics. In an Esaki spin-diode structure of n-(In,Fe)As/p-InAs, we observed the spin-split conduction band of (In,Fe)As for the first time by using the tunneling spectroscopy method. We also fabricated field-effect transistors with an (In,Fe)As quantum well, and electrically control the Curie temperature of the (In,Fe)As quantum well using the wave function engineering method. Our results provide an approach for versatile, low power, and ultrafast manipulation of magnetization.

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Fe-based carrier-induced ferromagnetic semiconductors and their applications to next-generation spin devices

Grant number：24686040 2012.4 - 2015.3

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)

PHAM NAM HAI

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Grant amount：\27040000 （ Direct Cost: \20800000 、 Indirect Cost：\6240000 ）

In this research, we aimed at fabrication of new Fe-based ferromagnetic semiconductors and development of new spin-devices utilizing them. The major results are as follows. First, we successfully fabricated (1) the world’s first n-type electron-induced ferromagnetic semiconductor (In,Fe)As. We observed (2) the quantum-size effect in quantum wells with ultrathin (In,Fe)As layers. We successfully controlled ferromagnetism by controlling the overlapping between Fe atoms and electron wavefunctions in spin-transistor structures with (In,Fe)As quantum wells for the first time. We then fabricated (3) a new p-type ferromagnetic semiconductor (Ga,Fe)Sb, and improved the Curie temperature of this material up to 230 K, which is the highest value ever reported for intrinsic ferromagnetic semiconductors. Our results indicate that Fe-based ferromagnetic semiconductors are very promising materials for semiconductor spintronics.

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Semiconductor Materials and Devices with Nonvolatile and Reconfigurable Functions

Grant number：23000010 2011 - 2015

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Specially Promoted Research

TANAKA Masaaki, OHYA Shinobu, NAKANE Ryosho, Pham Nam Hai, PALMSTROM Chris

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Grant amount：\539110000 （ Direct Cost: \414700000 、 Indirect Cost：\124410000 ）

By introducing magnetic atoms and materials into semiconductor materials and devices, we have successfully created new ferromagnetic semiconductors and ferromagnet/semiconductor hybrid structures to utilize not only charge transport of carriers but also spin degrees of freedom, and have realized a variety of new functionalities. Using these materials, we have designed and fabricated new semiconductor spintronics devices, in particular spin transistors, with spin-related functions, and have proved their device operation principles. Our results pave the way to the applications to non-volatile memory and reconfigurable logic circuitry.

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磁性体/半導体ハイブリッドナノ構造におけるスピン関連現象とデバイス応用

Grant number：23241044 2011

日本学術振興会科学研究費助成事業基盤研究(A)

田中雅明, 大矢忍, 中根了昌, ファムナムハイ

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Grant amount：\16770000 （ Direct Cost: \12900000 、 Indirect Cost：\3870000 ）

「磁性体/半導体ハイブリッドナノ構造におけるスピン関連現象とデバイス応用」を目的とした研究を開始した。ここで「磁性体/半導体ハイブリッドナノ構造」として対象とする材料系は、(a)GaMnAsやInGaMnAsを含む強磁性半導体ヘテロ構造、(b)MnAsナノ微粒子を埋め込んだGaAsとそのヘテロ構造、(c)強磁性金属薄膜/半導体ヘテロ構造である。これらの磁性体/半導体ハイブリッドナノ構造において、(1)エピタキシャル成長と形成技術の確立、(2)スピン依存伝導の理解と制御、磁気抵抗効果の増大、高温動作化、(3)スピン依存伝導デバイス(2端子素子、3端子素子)の試作、動作原理の確立を目指し、材料科学、物性の理解と制御からデバイス応用まで系統的に研究を行うことを目指している。
平成23年度には、磁性体/半導体ハイブリッドナノ構造(上記(a)(b)(c))のエピタキシャル成長と形成技術を確立しつつある。スピン依存伝導の理解と制御を行うため、まず2端子デバイスとして、強磁性半導体ヘテロ構造からなる強磁性トンネル接合素子、および強磁性ナノ微粒子を含む強磁性トンネル接合素子を作製し、そのスピン依存トンネル伝導の実験を行った。共鳴トンネル効果による磁気抵抗効果の増大、共鳴トンネル分光によるGaMnAsのバンド構造とフェルミ準位の解明を行った。その結果、どのような電気的・磁気的性質をもつGaMnAsにおいてもフェルミ準位は価電子帯から数十meV程度上の禁制帯中に存在し、不純物バンドによる伝導が支配的であることを明らかにした。平成23年6月以降は特別推進研究に移行して、より幅広い研究を行っている。

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Spin motive-force device with zinc-blende MnAs nanoparticles

Grant number：22760225 2010 - 2011

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)

PHAM Nam hai

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Grant amount：\4160000 （ Direct Cost: \3200000 、 Indirect Cost：\960000 ）

We aimed at the development of fabrication technology of homogeneous ferromagnetic MnAs nanoparticles embedded in a GaAs matrix for semiconductor spintronic applications. We successfully developed(1) the spinodal decomposition technique using the phase decomposition diagram for fabrication of homogenous MnAs nanoparticles. Using this technique, we successfully fabricated(2) single electron transistors with strong spin accumulation and long spin relaxation time, and(3) double barrier tunnel junctions with zinc-blended MnAs nanoparticles and non-magnetic electrodes with magnetoresistance enhanced by in-elastic co-tunneling.

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Reconfigurable Nano-Spin Devices

Grant number：18106007 2006 - 2010

Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)

TANAKA MASAAKI, OHYA Shinobu, SUGAHARA Satoshi, NAKANE Ryosho

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Grant amount：\101270000 （ Direct Cost: \77900000 、 Indirect Cost：\23370000 ）

We aimed at the development of basic technologies for reconfigurable nano-scale spin devices that cannot be realized by the conventional semiconductor device technology. We proposed new semiconductor-based device structures with spin-degrees of freedom, and fabricate the reconfigurable devices (in which the device functions can be reprogrammed after fabricating the devices), and demonstrated the device operation principles. We studied the following three types of spin devices.
(1) Group-IV-semiconductor based MOSFET planer-type spin devices
(2) III-V-semiconductor based heterojunction spin devices
(3) Single-electron type spin transistors based on hybrid materials consisting of ferromagnetic nano-particles and semiconductors.

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