Laser-induced Precession of Magnetization in GaMnAs

TL;DR

This paper demonstrates laser-induced precession of magnetization in GaMnAs using time-resolved magneto-optical Kerr effect, revealing intrinsic ferromagnetic dynamics without external magnetic fields.

Contribution

It provides a detailed analysis of the TR-MOKE signals, distinguishing the ferromagnetic precession from other contributions, advancing understanding of ultrafast spin dynamics in GaMnAs.

Findings

Laser pulses induce precession of Mn spins in GaMnAs.

Oscillatory signals are directly linked to ferromagnetic order.

Precession occurs even without external magnetic fields.

Abstract

We report on the photo-induced precession of the ferromagnetically coupled Mn spins in (Ga,Mn)As, which is observed even with no external magnetic field applied. We concentrate on various experimental aspects of the time-resolved magneto-optical Kerr effect (TR-MOKE) technique that can be used to clarify the origin of the detected signals. We show that the measured data typically consist of several different contributions, among which only the oscillatory signal is directly connected with the ferromagnetic order in the sample.