# Spin pumping into superconductors: A new probe of spin dynamics in a superconducting thin film

## TL;DR

This paper theoretically investigates spin pumping into superconductors, revealing a coherence peak below Tc that persists despite spin-orbit scattering, offering a new method to study spin dynamics in superconducting thin films.

## Contribution

It introduces a theoretical framework accounting for impurity spin-orbit scattering in spin pumping into superconductors, predicting a coherence peak below Tc.

## Key findings

- A pronounced coherence peak appears below Tc.
- The coherence peak persists despite spin-orbit scattering.
- Provides a new method to study spin susceptibility in superconductors.

## Abstract

Spin pumping refers to the microwave-driven spin current injection from a ferromagnet into the adjacent target material. We theoretically investigate the spin pumping into superconductors by fully taking account of impurity spin-orbit scattering that is indispensable to describe diffusive spin transport with finite spin diffusion length. We calculate temperature dependence of the spin pumping signal and show that a pronounced coherence peak appears immediately below the superconducting transition temperature Tc, which survives even in the presence of the spin-orbit scattering. The phenomenon provides us with a new way of studying the dynamic spin susceptibility in a superconducting thin film. This is contrasted with the nuclear magnetic resonance technique used to study a bulk superconductor.