Magnetic proximity in a superconductor-ferromagnetic-superconductor epitaxial system

The superconductor-ferromagnetic insulator-superconductor (SU-FMI-SU) junctions, where the superconducting order parameter exhibits a π phase difference across the FMI layer, are opening new avenues in the field of topological quantum computation. However, establishing the π phase across the junction requires the optimization of the magnetic properties of FMI layer as well as the induced magnetism at the SU-FMI interface. With this proposal, we aim to estimate the correlation in between the structural characteristics of FMI layer (thickness and homogeneity) and the interfacial magnetic coupling at SU-FMI interface. We have already performed a test experiment on D17 at ILL on one of these structures with 4nm thickness of FMI and, we have observed the signatures of magnetic proximity effect across superconducting transition temperature.

超导体-铁磁绝缘体-超导体（SU-FMI-SU）结，其超导序参量在铁磁绝缘层（FMI）两侧呈现π相位差，为拓扑量子计算领域开辟了全新研究路径。然而，要在该结中实现π相位差，需同时优化铁磁绝缘层的磁学特性，以及超导体与铁磁绝缘层界面处的感应磁性。本研究提案旨在探究铁磁绝缘层的结构特征（厚度与均匀性）与超导体-铁磁绝缘层界面磁耦合之间的关联。我们已在国际劳厄-朗之万研究所（Institut Laue-Langevin, ILL）的D17实验站，针对一款铁磁绝缘层厚度为4nm的该类结构开展了测试实验，并观测到了超导转变温度下跨界面的磁邻近效应特征。