Publishing type：Research paper (scientific journal)  

DOI： 10.1080/14686996.2024.2423600

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

<jats:title>Abstract</jats:title><jats:p>Iron-based 1111-type superconductors display high critical temperatures and relatively high critical current densities <jats:italic>J</jats:italic><jats:sub>c</jats:sub>. The typical approach to increasing <jats:italic>J</jats:italic><jats:sub>c</jats:sub> is to introduce defects to control dissipative vortex motion. However, when optimized, this approach is theoretically predicted to be limited to achieving a maximum <jats:italic>J</jats:italic><jats:sub>c</jats:sub> of only ∼30% of the depairing current density <jats:italic>J</jats:italic><jats:sub>d</jats:sub>, which depends on the coherence length and the penetration depth. Here we dramatically boost <jats:italic>J</jats:italic><jats:sub>c</jats:sub> in SmFeAsO<jats:sub>1–<jats:italic>x</jats:italic></jats:sub>H<jats:sub><jats:italic>x</jats:italic></jats:sub> films using a thermodynamic approach aimed at increasing <jats:italic>J</jats:italic><jats:sub>d</jats:sub> and incorporating vortex pinning centres. Specifically, we reduce the penetration depth, coherence length and critical field anisotropy by increasing the carrier density through high electron doping using H substitution. Remarkably, the quadrupled <jats:italic>J</jats:italic><jats:sub>d</jats:sub> reaches 415 MA cm<jats:sup>–2</jats:sup>, a value comparable to cuprates. Finally, by introducing defects using proton irradiation, we obtain high <jats:italic>J</jats:italic><jats:sub>c</jats:sub> values in fields up to 25 T. We apply this method to other iron-based superconductors and achieve a similar enhancement of current densities.</jats:p>

DOI： 10.1038/s41563-024-01952-7

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Publishing type：Research paper (scientific journal)   Publisher：American Chemical Society (ACS)  

DOI： 10.1021/acs.chemmater.4c00724

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

<jats:p>FeSb2 is known as a potential low-temperature thermoelectric material with the record-high power factor (PF) originating from the huge phonon drag thermopower (Sg). However, the Sg contribution to PF has been observed only at very low temperatures (T) &amp;lt; 40 K. In this paper, we found that the Sg persists at much higher T up to 240 K and enhances PF in FeSb2 thin films deposited on SrTiO3 single crystals. The FeSb2 films showed phonon drag Sg peak at T ∼ 60 K, and the Sg peak value was largely enhanced from 56 to 208 μV/K by varying film thicknesses from 10 to 100 nm. Due to thickness-dependent Sg contribution, the maximum PF = 31.3 μW/(cm K2) was obtained for a 37-nm thick film. In addition, the onset temperature, where Sg starts to appear, can be largely increased due presumably to the enhanced electron–phonon interaction by phonon leakage from the SrTiO3 substrate to the thin FeSb2 layer. Heterostructuring with an oxide would be an effective approach to enhance the phonon drag effect to increase PF in higher T regions for future thermoelectric cooling and energy conversion devices.</jats:p>

DOI： 10.1063/5.0204885

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Publishing type：Research paper (scientific journal)   Publisher：Royal Society of Chemistry (RSC)  

DOI： 10.1039/d4tc01116c

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Poster presentation  

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Language：English   Presentation type：Poster presentation  

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