Creation of all-epitaxial oxide superconducting spin valve using new rare earth monoxide

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15440
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Tohoku University
• Principal Investigator: Kaminaga Kenichi 東北大学, 工学研究科, 助教 (50831301)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: スピントロニクス / 超伝導 / パルスレーザー堆積法 / PLD / 酸化物 / 希土類単酸化物 / 電気化学

Outline of Final Research Achievements

A superconducting spin valve (SSV) device, in which a superconductor is sandwiched between two ferromagnetic insulators in the upper and lower layers, is a post-Moore technology that performs zero-resistance switching by controlling the parallel and antiparallel spin states of the ferromagnetic layers. In this study, we aimed to fabricate EuO/LaO/EuO SSV devices with coherent and steep junction interfaces with aligned crystallographic orientation by epitaxy technique to combine the ferromagnetic insulator EuO, a rare earth single oxide with the same rock salt structure as the new superconductor LaO, which was discovered by the principal investigator in 2018. Although the SSV devices could not be completed due to the transfer during the research period and the long interruption of experiments due to the Corona disaster, we discovered an electrochemical insitu characterization method for the semiconductor properties of EuO thin films in the course of the research.

Free Research Field

酸化物エレクトロニクス

Academic Significance and Societal Importance of the Research Achievements

本研究成果の学術的意義として、これまで作製自体の困難さゆえに単層での作製・評価に限られてきた希土類単酸化物(REO)研究を大きく領域拡大できたことが挙げられる。三層のSSV素子の完成には至らなかったもののLaO/EuO, Ag/EuO二層ヘテロ構造における特異なスピン特性や電気化学特性の発現を確認できたので、本研究を取っ掛かりに今後様々なREOヘテロの組合せを試みることでトポロジカル物性などの新奇物性開拓につながる可能性が高い。また、Agを用いたEuO薄膜のその場電気化学評価手法は他の大気不安定な準安定物質薄膜の評価に展開できることが期待される。