Magnetocrystalline anisotropy energy and Gilbert damping of two-dimensional half-metallic RhX2 (X = I, Br, Cl) ferromagnets: Density functional theory study

This work studies the monolayer rhodium dihalides family, RhX2 (where X = I, Br, Cl), using density functional theory. We first calculate the spin-polarized electronic band structure, revealing a wide intrinsic half-metallic gap (>1.1 eV) in the down spin bands of RhX2 monolayers. We then calculate the magnetocrystalline anisotropy energy (EMCA) and Gilbert damping (α), which originate from the spin–orbit coupling (SOC) phenomenon. We use the force theorem for EMCA calculation that results in substantial in-plane anisotropy in RhI2 (−2.31 meV/unit cell) and RhBr2 (−0.52 meV/unit cell), whereas small perpendicular anisotropy in RhCl2 (0.04 meV/unit cell) monolayers. To calculate α, we employ the Kambersky’s torque–torque correlation model and it comes out relatively low (i.e., 0.0212, 0.0079, and 0.0040 for RhI2, RhBr2, and RhCl2, respectively). The Curie temperature of these crystals is calculated using the Ising model and spin-wave theory. This work highlights the importance of 2D RhX2 half-metallic ferromagnets in the fabrication of future nanoscale spintronic devices.