Abstract

A conventional superconductor sandwiched between two ferromagnets can maintain coherent equilibrium spin current. In this talk, I discuss the basic phenomena such as magnetic proximity effect in ferromagnetic insulator/superconductor heterostructures and show how they enable a spin supercurrent through the superconductor mediated by odd-frequency spin correlations. I make an analogue with a Josephson effect, and show how the current-angle relation can be accessed in experiments on dynamic magnetization. Concentrating on the magnetic hysteresis and the ferromagnetic resonance response, I discuss how the spin supercurrent affects the magnetization dynamics of the two ferromagnets. In the studied system, there is a competition between spin supercurrent mediated static exchange contribution and a dynamic spin pumping contribution. Depending on the relative strength of these two contributions, the interaction between magnetic modes can either result an avoided crossing or mode locking.

https://doi.org/10.1103/PhysRevLett.128.167701