# Determination of spin relaxation time and spin diffusion length by oscillation of spin pumping signal

## TL;DR

This paper presents a theoretical method to determine spin relaxation time and diffusion length by analyzing oscillations in spin pumping signals influenced by external magnetic fields.

## Contribution

It introduces a novel approach using spin precession and diffusion to simultaneously measure spin relaxation time and length in spin pumping systems.

## Key findings

- Spin accumulation direction can be controlled by external magnetic fields.
- Inverse spin Hall voltage sign changes with magnetic field adjustments.
- Spin relaxation time and diffusion length are extractable from signal oscillations.

## Abstract

We theoretically investigate a manipulation method of nonequilibrium spin accumulation in the paramagnetic normal metal of a spin pumping system, by using the spin precession motion combined with the spin diffusion transport. We demonstrate based on the Bloch-Torrey equation that the direction of the nonequilibrium spin accumulation is changed by applying an additional external magnetic field, and consequently, the inverse spin Hall voltage in an adjacent paramagnetic heavy metal changes its sign. We find that the spin relaxation time and the spin diffusion length are simultaneously determined by changing the magnitude of the external magnetic field and the thickness of the normal metal in a commonly-used spin pumping system.