Matsuki Hisakazu, Hijano Alberto, Mazur Grzegorz P, Ilić Stefan, Wang Binbin, Alekhina Iuliia, Ohnishi Kohei, Komori Sachio, Li Yang, Stelmashenko Nadia, Banerjee Niladri, Cohen Lesley F, McComb David W, Bergeret F Sebastián, Yang Guang, Robinson Jason W A
Department of Materials Science & Metallurgy, University of Cambridge, Cambridge, UK.
Centro de Física de Materiales (CFM-MPC) Centro Mixto CSIC-UPV/EHU, Donostia-San Sebastián, Spain.
Nat Commun. 2025 Jul 1;16(1):5674. doi: 10.1038/s41467-025-61267-2.
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) to parallel (P) and antiparallel (AP) magnetisation-orientations of the F layers, corresponding shifts in T (i.e. ΔT = T - T) are lower than predicted with ΔT only a small fraction of T, 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/T 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.
1966年，皮埃尔 - 吉勒·德热纳提出了一种在磁性器件中开启和关闭超导性的非挥发性机制。这涉及到一个夹在铁磁（F）绝缘体之间的超导体（S），其中净磁交换场可以通过F层的磁化方向来控制。由于超导开关在一系列应用中具有吸引力，因此对F/S/F结构进行了广泛的研究。尽管这些研究已经证明了超导临界温度（T）对F层平行（P）和反平行（AP）磁化方向的敏感性，但T的相应变化（即ΔT = T - T）低于预测值，ΔT仅为T的一小部分，这阻碍了应用的发展。在这里，我们报道了EuS/Au/Nb/EuS结构，其中EuS是一种绝缘铁磁体，Nb是超导体，Au是重金属。对于P磁化，该结构中的超导态被猝灭到最低测量温度20 mK，这意味着ΔT/T实际上为1。这种所谓的“绝对开关”效应的关键在于EuS/Au界面处有相当大的自旋混合电导，这确保了强大的磁近邻效应，释放了F/S/F开关在低功耗电子学方面的潜力。
