Dynamics of a domain wall and spin-wave excitations driven by a mesoscopic current

TL;DR

This paper investigates how a spin-polarized current influences domain wall motion and spin-wave excitations in mesoscopic systems, revealing velocity behaviors dependent on Fermi and exchange energies through numerical simulations.

Contribution

It provides a detailed numerical analysis of domain wall dynamics considering spin-mixing effects, highlighting differences from adiabatic predictions based on Fermi energy relative to exchange energy.

Findings

Spin precession induces spin wave excitations affecting domain wall displacement.

Average domain wall velocity is significantly reduced compared to adiabatic limit when $E_{F}>J_{sd}$.

Residual domain wall velocity persists below critical current for $E_{F}<J_{sd}$.

Abstract

The dynamics of a domain wall driven by a spin-polarized current in a mesoscopic system is studied numerically. Spin-mixing in the states of the conduction electrons is fully taken into account. When the Fermi energy of the electrons is larger than the exchange energy ($E_{\rm F}>J_{\rm sd}$), the spin precession induces spin wave excitations in the local spins which contribute towards the displacement of the domain wall. The resulting average velocity is found to be much smaller than the one obtained in the adiabatic limit. For $E_{\rm F}<J_{\rm sd}$, the results are consistent with the adiabatic approximation except for the region below the critical current where a residual domain wall velocity is found.