Optical detection of spin transport in non-magnetic metals

TL;DR

This study uses Brillouin light scattering microscopy to detect and analyze spin transport in non-magnetic metals induced by spin pumping from a ferromagnetic layer, revealing relaxation times of the spin current.

Contribution

It demonstrates a method to measure spin transport in non-magnetic metals and quantifies the transverse relaxation time of the pumped spin current.

Findings

Spin pumping induces measurable magnetization in metals.

Adding an insulating layer controls spin pumping efficiency.

Transverse relaxation time is significantly shorter than longitudinal.

Abstract

We determine the dynamic magnetization induced in non-magnetic metal wedges composed of silver, copper and platinum by means of Brillouin light scattering (BLS) microscopy. The magnetization is transferred from a ferromagnetic Ni80Fe20 layer to the metal wedge via the spin pumping effect. The spin pumping efficiency can be controlled by adding an insulating but transparent interlayer between the magnetic and non-magnetic layer. By comparing the experimental results to a dynamical macroscopic spin-transport model we determine the transverse relaxation time of the pumped spin current which is much smaller than the longitudinal relaxation time.