Topology and Magnetism in Monolayers and Bilayers of ReX₃ (X = Br, I)

Two-dimensional (2D) van der Waals (vdW) magnets such as transition metals (TM) halides exhibiting topological states have provided a fertile ground for spintronic and quantum computing applications. In TM halides the presence of topologically protected states depends on the delicate balance of near degenerate interactions: (1) magnetic exchange interaction, (2) interlayer vdW interactions, and (3) amplified spin-orbit coupling (SOC). In this contribution, we have computed electronic, magnetic and topological properties of 2D (mono- and bi-layers) of ReX₃ (X = Br, I) with density functional theory (DFT) including vdW interactions and SOC. We report for the first-time layer-dependent magnetism in ReX₃ (X = Br, I), with intralayer ferromagnetism and interlayer antiferromagnetism. Moreover, we find that emerging topological states in these materials depend strongly on the fidelity of the electronic structure description. Our analysis shows that additional biases may be needed to induce topologically protected states in these materials, that allow for improved decoherence times with possible application to quantum computers.