A recent proof of concept showed that cavity photons can mediate superconducting (SC) signatures to a ferromagnetic insulator (FI) over a macroscopic distance [Phys. Rev. B, 102, 180506(R) (2020)]. In contrast with conventional proximity systems, this facilitates long-distance FI\unicodex2013SC coupling, local subjection to different drives and temperatures, and studies of their mutual interactions without proximal disruption of their orders. Here we derive a microscopic theory for these interactions, with an emphasis on the leading effect on the FI, namely, an induced anisotropy field. In an arbitrary practical example, we find an anisotropy field of 14\unicodex201316μT, which is expected to yield an experimentally appreciable tilt of the FI spins for low-coercivity FIs such as Bi-YIG. We discuss the implications and potential applications of such a system in the context of superconducting spintronics.
@article{arxiv.2209.09308,
title = {Cavity-mediated superconductor$\unicode{x2013}$ferromagnetic insulator coupling},
author = {Andreas T. G. Janssønn and Henning G. Hugdal and Arne Brataas and Sol H. Jacobsen},
journal= {arXiv preprint arXiv:2209.09308},
year = {2023}
}