Structural and magnetic dynamics of a laser induced phase transition in FeRh

TL;DR

This study investigates the ultrafast structural and magnetic phase transition in FeRh induced by laser pulses, revealing distinct timescales for domain nucleation and realignment, and highlighting the role of sound speed in phase coexistence.

Contribution

It presents a combined experimental and modeling analysis of the laser-induced phase transition in FeRh, emphasizing the different dynamics of structural and magnetic responses.

Findings

Structural domain nucleation occurs in ~30 ps.

Magnetic domain realignment occurs in ~60 ps.

Phase transition dynamics are limited by the speed of sound.

Abstract

We use time-resolved x-ray diffraction and magnetic optical Kerr effect to study the laser induced antiferromagnetic to ferromagnetic phase transition in FeRh. The structural response is given by the nucleation of independent ferromagnetic domains (\tau_1 ~ 30ps). This is significantly faster than the magnetic response (\tau_2 ~ 60ps) given by the subsequent domain realignment. X-ray diffraction shows that the two phases co-exist on short time-scales and that the phase transition is limited by the speed of sound. A nucleation model describing both the structural and magnetic dynamics is presented.