Topological spin textures in an insulating van der Waals magnet*

Generation and control of topological spin textures constitutes one of the most exciting challenges of modern spintronics given their potential applications in information storage technologies. Of particular interest are magnetic insulators, which due to low damping, absence of Joule heating and reduced dissipation could provide energy-efficient spin-textures platform. Here we demonstrated that the interplay between sample thickness, external magnetic fields and optical excitations can generate a prolific paramount of spin textures, and their coexistence in insulating CrBr3 van der Waals (vdW) ferromagnets. Using high-resolution magnetic force microscopy and large-scale micromagnetic simulation methods, we demonstrated the existence of a T-B phase diagram over a large range of temperatures and magnetic fields where different stripe domains, skyrmion crystals and magnetic domains exist but can be intrinsically selected or transformed to each-other via a phase-switch mechanism. The topological-phase transformation between the different magnetic objects could be further inspected by standard photoluminescence optical probes resolved by circular polarization indicative of an existance of exciton-skyrmion coupling mechanism. Our findings identified vdW magnetic insulators as a promising framework of materials for the manipulation and generation of highly ordered skyrmion lattices relevant for device integration at the atomic level.