Probing the spin polarization of current by soft X-ray imaging of current-induced magnetic vortex dynamics

TL;DR

This study uses time-resolved soft X-ray microscopy to visualize magnetic vortex dynamics in Permalloy disks, revealing the vortex core motion and quantifying the current's spin polarization with high spatial resolution.

Contribution

It demonstrates a novel imaging approach to directly observe vortex dynamics and accurately measure spin polarization in magnetic materials.

Findings

Vortex core exhibits resonant motion under current.

Spin polarization of Permalloy current is 0.67 ± 0.16.

High-resolution imaging captures vortex behavior at nanometer scale.

Abstract

Time-resolved soft X-ray transmission microscopy is applied to image the current-induced resonant dynamics of the magnetic vortex core realized in a micronsized Permalloy disk. The high spatial resolution better than 25 nm enables us to observe the resonant motion of the vortex core. The result also provides the spin polarization of the current to be 0.67 +/-0.16 for Permalloy by fitting the experimental results with an analytical model in the framework of the spin-transfer torque.