Two-dimensional Janus SVAN2 (A = Si, Ge) monolayers with intrinsic semiconductor character and room temperature ferromagnetism: tunable electronic properties via strain and an electric field†

Abstract

In the context of developing next-generation information technology, two-dimensional materials with inherent ferromagnetism, a Curie temperature above room temperature, and significant magnetic anisotropy hold great promise. In this work, we employed first-principles calculations to investigate a novel two-dimensional Janus structure, namely SVAN₂ (A = Si, Ge). Our findings reveal that these structures are not only dynamically and thermally stable, but also exhibit semiconductor properties alongside their ferromagnetic states. The Janus SVSiN₂ monolayer exhibits an in-plane easy axis, while the SVGeN₂ monolayer shows an out-of-plane easy axis, both characterized by a significant magnetic anisotropy energy (129 and 172 μeV, respectively). Notably, through Monte Carlo simulation, we found that the Curie temperature of the SVSiN₂ monolayer is 330 K, which is higher than room temperature. Finally, by applying biaxial strain and an external electric field, we successfully regulated the electronic properties of the SVAN₂ (A = Si, Ge) monolayers, enabling a transition from semiconductor to half-metallic behavior. These remarkable electronic and magnetic properties make the Janus SVAN₂ (A = Si, Ge) monolayers promising candidate materials for spin electron applications.