Ferromagnetic topological states in monolayer vanadium halides toward heterostructure applications

Topological states in two-dimensional materials have garnered significant research attention in recent years, particularly those with intrinsic magnetic orderings, which hold great potential for spintronic applications. Through theoretical calculations, we unveil the superior band topology of monolayer vanadium trihalides, with a specific focus on V2Cl6. These two-dimensional compounds exhibit a half-metallic ferromagnetic ground state, showcasing excellent thermodynamic and mechanical stabilities. Remarkably, clean band crossings with complete spin polarization manifest as phase transitions between Weyl semimetal states and quantum anomalous Hall states under different magnetization directions, and both topological phases yield prominent edge states. Furthermore, Monte Carlo simulations estimate a high Curie temperature of up to 381.3 K, suggesting the potential for spintronic development above room temperature. Taking a step forward, we construct two heterojunctions utilizing selected substrates, MoS2 and h-BN. These substrates not only facilitate a suitable lattice integration but also have a negligible impact on the half-metallicity and band topology. These findings lay the groundwork for exploring practical applications of two-dimensional ferromagnetic topological states. Importantly, the presented material candidates have the potential to accelerate the development of room temperature applications and integrate spintronic devices.