Transient Magnetoelastic Coupling in CrSBr

Abstract: Recent research has revealed remarkable properties of the two-dimensional (2D) van der Waals layered crystal CrSBr, which is both a semiconductor and an A-type antiferromagnet. Here we show the role of strong magnetoelastic coupling in the generation and propagation of coherent magnons in CrSBr. Time and spatially resolved magneto-optical Kerr effect (tr-MOKE) microscopy reveals two time-varying transient strain fields induced by out-of-plane transverse and in-plane longitudinal lattice displacements. These transient strain fields launch coherent wavepackets of magnons, optical and acoustic at 24.6 GHz and 33.4 GHz, respectively. These findings suggest mechanisms for controlling and manipulating coherent magnons from distinct magnetoelastic couplings in this 2D van der Waals magnetic semiconductor.