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.