Theory of spin and lattice wave dynamics excited by focused laser pulses

TL;DR

This paper presents a comprehensive theory describing how ultrafast focused laser pulses excite spin wave dynamics in magnetic films, accounting for various modes, fields, and damping effects, with validation against experimental data.

Contribution

It introduces a detailed theoretical model that includes volume and surface spin wave modes, laser spot size, and damping, advancing understanding of laser-induced spin wave excitation.

Findings

Laser pulses generate a broad spectrum of spin waves.

The model aligns well with recent experimental observations.

Sound waves from local heating significantly contribute to spin wave excitation.

Abstract

We develop a theory of the spin wave dynamics excited by ultrafast focused laser pulses in a magnetic film. We take into account both volume and surface spin wave modes in the presence of applied, dipolar and magnetic anisotropy fields and include the dependence on laser spot exposure size and magnetic damping. We show that the sound waves generated by local heating by an ultrafast focused laser pulse can excite a wide spectrum of spin waves (on top of a dominant magnon-phonon contribution). Good agreement with recent experiments supports the validity of the model.