Light-induced magnetization precession in GaMnAs

TL;DR

This paper investigates the ultrafast magnetization dynamics in ferromagnetic GaMnAs using femtosecond laser pulses, revealing the oscillatory Kerr rotation linked to magnetic order and the influence of annealing on damping.

Contribution

It provides new insights into light-induced magnetization precession mechanisms and the effect of annealing on Gilbert damping in GaMnAs.

Findings

Oscillatory Kerr rotation is directly related to ferromagnetic order.

Magnetization precession damping is significantly affected by annealing.

Multiple contributions to transient Kerr signals were identified.

Abstract

We report dynamics of the transient polar Kerr rotation (KR) and of the transient reflectivity induced by femtosecond laser pulses in ferromagnetic (Ga,Mn)As with no external magnetic field applied. It is shown that the measured KR signal consist of several different contributions, among which only the oscillatory signal is directly connected with the ferromagnetic order in (Ga,Mn)As. The origin of the light-induced magnetization precession is discussed and the magnetization precession damping (Gilbert damping) is found to be strongly influenced by annealing of the sample.