Spin-wave instabilities in spin-transfer-driven magnetization dynamics

TL;DR

This paper investigates the stability of magnetization precessions in spin-transfer devices, identifying how spin-wave interactions and external conditions influence their stability through analytical and numerical methods.

Contribution

It introduces a generalized approach to analyze spin-wave instabilities in spin-transfer-driven magnetization dynamics, providing stability diagrams and insights into stabilizing effects of fields and currents.

Findings

Instabilities are caused by magnetostatically coupled spin-waves.

Larger magnetic fields and currents stabilize magnetization precessions.

Analytical results align with numerical simulations.

Abstract

We study the stability of magnetization precessions induced in spin-transfer devices by the injection of spin-polarized electric currents. Instability conditions are derived by introducing a generalized, far-from-equilibrium interpretation of spin-waves. It is shown that instabilities are generated by distinct groups of magnetostatically coupled spin-waves. Stability diagrams are constructed as a function of external magnetic field and injected spin-polarized current. These diagrams show that applying larger fields and currents has a stabilizing effect on magnetization precessions. Analytical results are compared with numerical simulations of spin-transfer-driven magnetization dynamics.