Current-induced magnetization dynamics in two magnetic insulators separated by a normal metal

TL;DR

This paper investigates how electric currents influence magnetization dynamics in layered magnetic insulators separated by a normal metal, highlighting the roles of spin Hall effects and spin pumping.

Contribution

It provides analytical expressions for damping and critical currents considering spin pumping, advancing understanding of current-induced magnetization control in insulator-based spin valves.

Findings

Current induces amplitude asymmetry in magnetization modes

Derived formulas for effective damping and critical currents

Potential experimental tests via ferromagnetic resonance

Abstract

We study the dynamics of spin valves consisting of two layers of magnetic insulators separated by a normal metal in the macrospin model. A current through the spacer generates a spin Hall current that can actuate the magnetization via the spin-transfer torque. We derive expressions for the effective Gilbert damping and the critical currents for the onset of magnetization dynamics including the effects of spin pumping that can be tested by ferromagnetic resonance experiments. The current generates an amplitude asymmetry between the in-phase and out-of-phase modes. We briefly discuss superlattices of metals and magnetic insulators.