Light-Induced Magnetic Precession in (Ga,Mn)As Slabs: Hybrid Standing-Wave Damon-Eshbach Modes

TL;DR

This paper investigates light-induced spin precessions in (Ga,Mn)As films, combining experimental observations with a comprehensive theoretical model to extract magnetic parameters and reveal surface anisotropy effects.

Contribution

It provides a complete theoretical framework linking light coupling to magnetization dynamics and determines key magnetic constants from experimental data.

Findings

Identification of hybrid standing-wave Damon-Eshbach modes

Quantification of exchange and anisotropy constants

Revelation of significant surface anisotropy contribution

Abstract

Coherent oscillations associated with spin precessions were observed in ultrafast optical experiments on ferromagnetic (Ga,Mn)As films. Using a complete theoretical description of the processes by which light couples to the magnetization, values for the exchange and anisotropy constants were obtained from the field-dependence of the magnon frequencies and the oscillation-amplitude ratios. Results reveal a relatively large negative contribution to the energy due to surface anisotropy leading to excitations that are a mixture of bulk waves and surface modes.