First-principles predictions of ferromagnetism in monolayers of the 2D materials Cr2X4Y (X = S, Se; Y = Ga, Ge, In, Sn)

Abstract Research on two-dimensional magnetic materials has gained significant attention in recent years owing to their unique thickness-dependent magnetism, tunable properties, and potential applications in spintronics, quantum computing, and next-generation data storage technologies. This study investigated the intrinsic ferromagnetic properties of Cr2X4Y (X = S, Se; Y = Ga, Ge, In, Sn) monolayers, with emphasis on their potential application in spintronic devices. Comprehensive stability analyses confirmed the feasibility of synthesizing these materials. Our results predict that all of these materials would exhibit robust ferromagnetism with magnetic moments of ∼4 μB per Cr atom and high Curie temperatures (Tc) ranging from 170 K to 691 K, with Cr2S4Ga achieving the highest Tc. The ferromagnetic behavior, attributed to superexchange interactions, remains stable under biaxial strain (−6% to 6%). Based on their electronic structures, half-metallicity is predicted for Cr2X4Y (Y = Ga, In), which enables 100% spin polarization, whereas Cr2X4Y (Y= Ge, Sn) are semiconductors with sizable band gaps. These findings indicate that the Cr2X4Y monolayers are promising candidates for room-temperature spintronic devices with tunable magnetic properties.