Two-dimensional Cr2GaX4 (X = S, Se, Te) monolayers: half-metallic intrinsic room temperature ferromagnets with large magnetic anisotropy

Abstract

Developing two-dimensional (2D) materials with robust ferromagnetism is highly desirable for spintronic applications. In this work, we have designed a series of intrinsic ferromagnetic Cr₂GaX₄ (X = S, Se, Te) monolayers using first-principles calculations. The magnetic exchange interactions were evaluated using the linear-response approach, and Monte Carlo simulations based on magnetic exchange constants yielded high Curie temperatures up to 436 K for Cr₂GaTe₄. Remarkably, Cr₂GaTe₄ was found to have a large magnetic anisotropy energy of 3.45 meV per Cr atom, making it a promising candidate for nanomagnet applications. The electronic structure reveals half-metallic behavior with band gaps over 3 eV in the minority spin channel. Furthermore, phonon spectra and elastic constant calculations confirm that the Cr₂GaX₄ (X = S, Se, Te) monolayers are dynamically and mechanically stable. Overall, this study demonstrates that intrinsically ferromagnetic Cr₂GaX₄ (X = S, Se, Te) monolayers with high Curie temperatures and magnetic anisotropy could enable exciting opportunities in 2D magnetic nanodevices.