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

DOI： 10.7566/jpsj.93.023702

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Authorship：Last author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：AIP Publishing  

Antiferromagnetic L12-Mn3Ir combines outstanding spin-transport properties with magnons in the terahertz (THz) frequency range. However, the THz radiation emitted by ultrafast spin-to-charge conversion via the inverse spin Hall effect remains unexplored. In this study, we measured the THz emission and transmission of a Permalloy/(111)-oriented L12-Mn3Ir multilayer by THz time-domain spectroscopy. The spin Hall angle was determined to be approximately constant at 0.035 within a frequency range of 0.3–2.2 THz, in comparison with the THz spectroscopy of a Permalloy/Pt multilayer. Our results not only demonstrate the potential of L12-Mn3Ir as a spintronic THz emitter but also provide insights into the THz spin transport properties of L12-Mn3Ir.

DOI： 10.1063/5.0168138

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Authorship：Last author   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

DOI： 10.1109/intermagshortpapers58606.2023.10308523

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Publishing type：Research paper (scientific journal)  

DOI： 10.1063/5.0152670

Web of Science

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：Frontiers Media SA  

All-optical helicity dependent switching (AO-HDS), deterministic control of magnetization by circularly polarized laser pulses, allows to efficiently manipulate spins without the need of a magnetic field. However, AO-HDS in ferromagnetic metals so far requires many laser pulses for fully switching their magnetic states. Using a combination of a short, 90-fs linearly polarized pulse and a subsequent longer, 3-ps circularly polarized pulse, we demonstrate that the number of pulses for full magnetization reversal can be reduced to four pulse pairs in a single stack of Pt/Co/Pt. The obtained results suggest that the dual-pulse approach is a potential route towards realizing efficient AO-HDS in ferromagnetic metals.

DOI： 10.3389/fnano.2022.765848

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Authorship：Lead author,　Corresponding author   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevb.102.100407

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.102.100407/fulltext

Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

DOI： 10.1080/08940886.2020.1725795

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

The explosive growth of data and its related energy consumption is pushing the need to develop energy-efficient brain-inspired schemes and materials for data processing and storage. Here, we demonstrate experimentally that Co/Pt films can be used as artificial synapses by manipulating their magnetization state using circularly polarized ultrashort optical pulses at room temperature. We also show an efficient implementation of supervised perceptron learning on an opto-magnetic neural network, built from such magnetic synapses. Importantly, we demonstrate that the optimization of synaptic weights can be achieved using a global feedback mechanism, such that the learning does not rely on external storage or additional optimization schemes. These results suggest that there is high potential for realizing artificial neural networks using optically controlled magnetization in technologically relevant materials, which can learn not only fast but also energy-efficient.

DOI： 10.1063/1.5087648

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

DOI： 10.7567/apex.11.073002

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Other Link： http://stacks.iop.org/1882-0786/11/i=7/a=073002?key=crossref.503890c369efec592ee575202e5f988f

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

DOI： 10.7567/apex.11.063002

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Other Link： http://stacks.iop.org/1882-0786/11/i=6/a=063002?key=crossref.e27eaeff315bc77f90626f20c1f42873

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

Abstract

Chiral spin textures of a ferromagnetic layer in contact to a heavy non-magnetic metal, such as Néel-type domain walls and skyrmions, have been studied intensively because of their potential for future nanomagnetic devices. The Dyzaloshinskii–Moriya interaction (DMI) is an essential phenomenon for the formation of such chiral spin textures. In spite of recent theoretical progress aiming at understanding the microscopic origin of the DMI, an experimental investigation unravelling the physics at stake is still required. Here we experimentally demonstrate the close correlation of the DMI with the anisotropy of the orbital magnetic moment and with the magnetic dipole moment of the ferromagnetic metal in addition to Heisenberg exchange. The density functional theory and the tight-binding model calculations reveal that inversion symmetry breaking with spin–orbit coupling gives rise to the orbital-related correlation. Our study provides the experimental connection between the orbital physics and the spin–orbit-related phenomena, such as DMI.

DOI： 10.1038/s41467-018-04017-x

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Other Link： https://www.nature.com/articles/s41467-018-04017-x

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevlett.120.157203

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevLett.120.157203/fulltext

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

DOI： 10.7567/apex.11.036601

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Other Link： http://stacks.iop.org/1882-0786/11/i=3/a=036601?key=crossref.b5373d2ad5055457557470726eb502bf

Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevb.96.214422

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.96.214422/fulltext

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

DOI： 10.7567/apex.10.073006

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Other Link： http://stacks.iop.org/1882-0786/10/i=7/a=073006?key=crossref.469dd3675e6fba97f95bd3726b7ce533

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

DOI： 10.7567/jjap.56.050305

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Other Link： http://stacks.iop.org/1347-4065/56/i=5/a=050305?key=crossref.8a210041720d19a65d4689f6aa53ffd4

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

Abstract

The electric field control of superparamagnetism is realized using a Cu/Ni system, in which the deposited Ni shows superparamagnetic behavior above the blocking temperature. An electric double-layer capacitor (EDLC) with the Cu/Ni electrode and a nonmagnetic counter electrode is fabricated to examine the electric field effect on magnetism in the magnetic electrode. By changing the voltage applied to the EDLC, the blocking temperature of the system is clearly modulated.

DOI： 10.7567/apex.10.013004

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Other Link： http://stacks.iop.org/1882-0786/10/i=1/a=013004?key=crossref.f7fa184efd405e5e06881f6192f56368

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

The electric field (EF) effect on the magnetic domain structure of a Pt/Co system was studied, where an EF was applied to the top surface of the Co layer. The width of the maze domain was significantly modified by the application of the EF at a temperature slightly below the Curie temperature. After a detailed analysis, a change in the microscopic exchange stiffness induced by the EF application was suggested to dominate the modulation of the domain width observed in the experiment. The accumulation of electrons at the surface of the Co layer resulted in an increase in the microscopic exchange stiffness and the Curie temperature. The result was consistent with the recent theoretical prediction.

DOI： 10.1063/1.4955265

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Publishing type：Research paper (scientific journal)   Publisher：American Physical Society (APS)  

DOI： 10.1103/physrevb.93.195168

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Other Link： http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevB.93.195168/fulltext

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

Abstract

Electric field effect on magnetism is an appealing technique for manipulating magnetization at a low energy cost. Here, we show that the local magnetization of an ultrathin Co film can be switched by simply applying a gate electric field without the assistance of any external magnetic field or current flow. The local magnetization switching is explained by nucleation and annihilation of magnetic domains through domain wall motion induced by the electric field. Our results lead to external-field-free and ultralow-energy spintronic applications.

DOI： 10.7567/apex.9.063004

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Other Link： http://stacks.iop.org/1882-0786/9/i=6/a=063004?key=crossref.42ad6db36633cfb740dd1d3c6079fe66

Authorship：Lead author   Publishing type：Research paper (scientific journal)   Publisher：IOP Publishing  

DOI： 10.7567/apex.6.073004

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

In this study, we have investigated magnetic domain wall motion under gate electric fields in a perpendicularly magnetized Co/Pt wire. The motion under a transparent gate electrode was directly monitored using a magneto-optical Kerr effect microscope. The domain wall velocity was determined as a function of temperature and gate voltage. It was found that this velocity could be modulated by up to two orders of magnitude by changing the gate voltage.

DOI： 10.7567/jjap.52.070206

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Other Link： https://iopscience.iop.org/article/10.7567/JJAP.52.070206/pdf