Laser‐induced switching of magnetization between multiple magnetic states has tremendous potential for data recording and storage applications. As a nonthermal phenomenon, photo‐magnetic switching stands out from various discovered switching mechanisms with its unparalleled energy efficiency. Dielectric rare‐earth iron garnet cubic crystals, where it has been observed, enrich magnetization dynamics with high symmetry and complicated magnetic anisotropy landscape, enabling storage of multiple bits of information in a single magnetic domain. In this work we demonstrate methods to control the photo‐magnetic torque, which sets the magnetization into motion and eventually determines both its trajectory and destination. We use the formalism based on Landau–Lifshitz–Gilbert dynamics with an effective anisotropy field originating in the photo‐magnetism and analyze the methods to modify the torque sign and magnitude. In particular, we demonstrate how varying equilibrium magnetization, light polarization, and using plasmonic excitations in metal‐dielectric hybrids enable steady control of the photo‐magnetic dynamics, which is key for the multistate switching. Our work outlines promising directions for future research towards highly efficient magnetic recording at the nanoscale.
Kazlou et al. (Thu,) studied this question.