Ultrafast optical observation of spin-pumping induced dynamic exchange coupling in ferromagnetic semiconductor/metal bilayer

TL;DR

This study uses ultrafast optical techniques to observe how spin pumping induces dynamic exchange coupling in a ferromagnetic semiconductor/metal bilayer, revealing temperature-dependent magnetic interactions.

Contribution

It provides direct optical evidence of dynamic exchange coupling driven by spin pumping in a ferromagnetic bilayer, highlighting temperature effects.

Findings

Enhanced dynamic exchange coupling observed at resonance.

Temperature dependence linked to ferromagnetism in (Ga,Mn)As.

Spin pumping significantly influences magnetization dynamics.

Abstract

Spin angular momentum transfer in magnetic bilayers offers the possibility of ultrafast and low-loss operation for next-generation spintronic devices. We report the field- and temperature- dependent measurements on the magnetization precessions in Co$_2$FeAl/(Ga,Mn)As by time-resolved magneto-optical Kerr effect (TRMOKE). Analysis of the effective Gilbert damping and phase shift indicates a clear signature of an enhanced dynamic exchange coupling between the two ferromagnetic (FM) layers due to the reinforced spin pumping at resonance. The temperature dependence of the dynamic exchange-coupling reveals a primary contribution from the ferromagnetism in (Ga,Mn)As.