Spin current and superconductivity in beta-tungsten

Research Project

Project/Area Number	17K19049
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Research Field	Applied condensed matter physics and related fields
Research Institution	The University of Tokyo
Principal Investigator	Hayashi Masamitsu 東京大学, 大学院理学系研究科(理学部), 准教授 (70517854)
Research Collaborator	KAWAGUCHI Masashi
Project Period (FY)	2017-06-30 – 2019-03-31
Project Status	Completed (Fiscal Year 2018)
Budget Amount *help	¥6,500,000 (Direct Cost: ¥5,000,000、Indirect Cost: ¥1,500,000) Fiscal Year 2018: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000) Fiscal Year 2017: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Keywords	超伝導 / スピン軌道相互作用 / タングステン / スピン流 / スピンエレクトロニクス
Outline of Final Research Achievements	The aim of this study is to reveal the relationship between the spin Hall angle and the superconducting transition temperatures in A15 structures. In this project, we have developed WC and MoN/W bilayer structures that exhibit relatively high superconducting transition temperature (Tc). In the latter, we found that the Tc is enhanced by superconducting proximity effect. We have also studied the superconducting properties of beta-W and found that the superconducting coherence length is ~7-14 nm.
Academic Significance and Societal Importance of the Research Achievements	本研究により、スピン軌道相互作用が大きく、かつ超伝導転移温度が液体ヘリウム温度（4.2K）よりも大きい物質を開拓することに成功した。これにより、スピン軌道相互作用が大きい超伝導物質へのスピン流注入やスピン流生成に関する実験が可能となる。また、ベータ-Wの面内臨界磁場が大きく、超伝導のコヒーレンス長が7-14 nm程度であることがわかり、大きなスピン軌道相互作用を有する物質における超伝導特性の知見が得られた。