Halogen-driven magnetic properties of two-dimensional binary and Janus Cr2XYSe2 (X, Y = F, Cl, Br, I) monolayers

Abstract

In this study, we investigate the structural, electronic, and magnetic properties of the orthorhombic phase of Cr₂XYSe₂ (X, Y = F, Cl, Br, I) two-dimensional monolayers using first-principles calculations based on density functional theory. The calculated exchange interaction parameters and magnetic anisotropies exhibit a strong dependence on both the chemical composition of the monolayers and the Hubbard parameter U. This finding indicates that the interplay between spin–orbit coupling and electron localization is crucial for stabilizing long-range magnetic order in these systems. Furthermore, the renormalized magnon spectrum derived from our calculations yields Curie temperatures of approximately 200 K for the iodine-based monolayers, the highest among the compositions studied, indicating the maximum thermal stability. The results of this investigation provide a comprehensive understanding of how chemical substitution, electron correlations, and symmetry reduction interact to control magnetism in two-dimensional materials. This study advances the understanding of magnetism in Cr₂XYSe₂ monolayers and establishes a distinct materials design framework for two-dimensional van der Waals magnetic systems.