Ultrafast strain excitation in highly magnetostrictive terfenol: Experiments and theory

We experimentally and analytically investigate laser excitation of picosecond longitudinal shear acoustic pulses in highly magnetostrictive terfenol-${\mathrm{TbFe}}_{2}$-epitaxial thin films. report a magnetoelastic mechanism for strain excitation, so-called direct transient demagnetostriction, which denotes the ultrafast laser-induced demagnetization release static built-in strains. From analytical considerations numerical modeling, we demonstrate that efficiency ultrashort strains generation strongly depends on magnetization orientation with respect to lattice crystallographic directions. Overall, our study provides insight into waves detection all sorts magnetic materials from laser-based mechanisms.