Single-pulse strain-induced precessional dynamics of magnetization in Co-doped iron garnet

Abstract

Ultrafast control of magnetization through lattice excitation provides a route to manipulating magnetic order on short timescales, yet the role of transient strain in driving magnetization dynamics remains poorly understood. Here, single-shot pump-probe magneto-optical microscopy is used to resolve the structural and magnetic responses of cobalt-doped yttrium iron garnet to individual 5-ps mid-infrared pulses. The excitation generates a localized strain field together with an outward-propagating elastic wave. Concurrently, the magnetic contrast decreases following excitation and subsequently reverses on a timescale of approximately 1.5-2 ns before recovering to its initial state. The structural and magnetic responses exhibit closely correlated wavelength and pulse-energy dependences, indicating a common excitation pathway. Micromagnetic simulations incorporating transient strain reproduce the precessional reorientation of the magnetization within individual domains while largely preserving the labyrinthine domain morphology. These results identify transient lattice deformation as the link between single-pulse mid-infrared excitation and reversible precessional magnetization dynamics in Co-doped yttrium iron garnet.