Toward Optically Induced Antiferromagnetic-to-Ferromagnetic Transitions in Few-Layer CrI₃ and Fe₃GeTe₂

Materials with controllable antiferromagnetic-to-ferromagnetic (AFM-FM) transitions are high interest targets for data storage research. AFM-FM transitions in few-layer van der Waals magnets, such as CrI₃ and Fe₃GeTe₂, have been addressed with electrostatic fields, bearing promise for compact on-chip memories. Here, we explore the possibility of all-optical AFM-FM switching in bi-layer CrI₃ and Fe₃GeTe₂ systems in theory, using Density Functional Theory (DFT) and tight-binding models, and experiment. We attempt to extend the analysis to describe AC fields through numerical evaluation of model Hamiltonians and Time Dependent Density Functional Theory (TDDFT). The latter reveals nearly adiabatic evolution of CrI₃ under mid-IR excitation, suggesting that the observed AFM-FM switching seen with the application of static fields may also be realized optically. Our experimental focus is the investigation of the 2D material Fe₃GeTe₂. We report on successful fabrication of few-layer Fe₃GeTe₂ samples and present a method for realizing the switch via a pump-probe Magneto-Optical-Kerr-Effect (MOKE) setup. Our models and measurements will further our understanding of ultrafast magnetism at the 2D limit.