[16a-S2_201-1~13] 10.4 半導体・トポロジカル・超伝導・強相関スピントロニクス

11:30 〜 11:45英語発表

[16a-S2_201-10] Realization of de Gennes’ Absolute Superconducting Switch with a Heavy Metal Interface

〇Hisakazu Matsuki^1,2,3, Alberto Hijano^4,5, Greg Mazur^3,6, Stefan Ilic^4,5, Binbin Wang⁷, Iuliia Alekhina³, Kohei Ohnishi^3,8, Sachio Komori^3,9, Yang Li³, Nadia Stelmashenko³, Niladri Banerjee¹⁰, Lesley Cohen¹⁰, David McComb⁷, Sebastian Bergeret⁴, Guang Yang^3,11, Jason Robinson³ (1.ICR, Kyoto Univ., 2.CSRN, Kyoto Univ., 3.Univ. of Cambridge, 4.CSIC-UPV/EHU, 5.Univ. of Jyvaskyla, 6.UCSB, 7.OSU, 8.Kindai Univ., 9.Nagoya Univ., 10.Imperial College, 11.Beihang Univ.)

キーワード：

superconductor、spintronics

In 1966, Pierre-Gilles de Gennes proposed a non-volatile mechanism for switching superconductivity on and off in a magnetic device. This involved a superconductor (S) sandwiched between ferromagnetic (F) insulators in which the net magnetic exchange field could be controlled through the magnetisation orientation of the F layers. Because superconducting switches are attractive for a range of applications, extensive studies have been carried out on F/S/F structures. Although these have demonstrated a sensitivity of the superconducting critical temperature (T_c) to parallel (P) and antiparallel (AP) magnetisation orientations of the F layers, corresponding shifts in T_c (i.e., ΔT_c = T_c,AP - T_c,P) are lower than predicted with ΔT_c only a small fraction of T_c,AP, precluding the development of applications. Here, we report EuS/Au/Nb/EuS structures where EuS is an insulating ferromagnet, Nb is a superconductor and Au is a heavy metal. For P magnetisations, the superconducting state in this structure is quenched down to the lowest measured temperature of 20 mK meaning that ΔT_c/T_c,AP is practically 1. The key to this so-called “absolute switching” effect is a sizable spin-mixing conductance at the EuS/Au interface which ensures a robust magnetic proximity effect, unlocking the potential of F/S/F switches for low power electronics.