Spin-polarized Current-induced Instability in Spin-Valve with Antiferromagnetic Layer

TL;DR

This paper models how spin-polarized currents can destabilize antiferromagnetic layers in spin-valves, revealing mechanisms like negative friction and frequency shifts that influence magnetic stability.

Contribution

It introduces a phenomenological model showing how spin currents affect AFM dynamics, including destabilization thresholds related to magnetic anisotropy.

Findings

Spin currents can induce negative friction in AFM.

Spin currents modify AFM spin-wave frequencies.

Destabilization threshold depends on magnetic anisotropy.

Abstract

In the framework of phenomenological model we consider dynamics of a compensated collinear antiferromagnet (AFM) in the presence of spin-polarised current. The model is based on the assumption that AFM spins are localised and spin torque is transferred to each magnetic sublattice independently. It is shown that in AFM spin current i) can be a source of the "negative friction"; and ii) modifies spin-wave frequencies. Equilibrium state of AFM can be destabilized by the current polarized in parallel to AFM vector. Threshold current at which the loss of stability takes place depends upon the magnetic anisotropy of AFM.