Excitation of spin dynamics by spin-polarized current in vortex state disks

TL;DR

This paper investigates how spin-polarized currents influence vortex-state disks, revealing threshold-dependent damping effects and dynamic precession behaviors relevant for spintronic applications.

Contribution

It demonstrates the threshold behavior of damping renormalization and describes the vortex precession dynamics under spin-polarized currents in vortex-state disks.

Findings

Effective damping is renormalized by spin-polarized current.

Zero damping occurs at a specific threshold current.

Vortex precession frequency increases with current.

Abstract

A spin-polarized current with the polarization perpendicular to the plane of a vortex-state disk results in renormalization of the effective damping for a given magnetization mode, and the effective damping becomes zero if the current exceeds a threshold value. The lowest threshold current corresponds to the lowest frequency vortex gyroscopic mode. For larger values of the current the dynamic magnetization state is characterized by precession of the vortex around the dot center with non-small amplitude and higher frequency.