All-Optical Control and Ultrafast Spin Dynamics in Van Der Waals Magnets

Despite tremendous interest in two-dimensional (2D) van der Waals (vdW) magnets, little is known about how laser pulses can affect their magnetic properties. Here, we demonstrate laser-induced manipulation of magnetic domains within 2D ferromagnets CrI
3
and Cr
2
Ge
2
Te
6
. We show that depending on the initial state of remanent magnetization, pumping with laser pulses can lead to randomly oriented sub-domains, generate different type of topological spin textures, and even induce a reversible transformation between them. Furthermore, by fabricating CrI
3
/WSe
2
vdW heterostructures, we can achieve full all-optical switching (AOS). Finally, by using time-resolved beam-scanning magneto-optical Kerr effect microscopy, we demonstrate how to modify the magnetization dynamics via thickness-dependent heat dissipation into the adjacent substrate.