Two-Dimensional Cr2X3S3 (X = Br, I) Janus Semiconductor with Intrinsic Room-Temperature Magnetism.

The exploration of two-dimensional (2D) semiconductors with intrinsic room-temperature magnetism for use in nanoscale spintronic devices is of particular interest. Recently, the ferromagnetic CrX3 monolayer (X = Br, I) has received growing attention, but low critical temperature hinders its practical applications in spintronics. Here, using first-principles calculations, we report 2D Cr2X3S3 (X = Br, I) Janus semiconductors with room-temperature magnetism by replacing one layer of halogon atoms with sulfur atoms in CrX3 monolayer. Our results demonstrate that Cr2Br3S3 and Cr2I3S3 Janus crystals are ferrimagnetic semiconductors, that maintain their magnetic order, with a direct bandgap of 1.19 and 0.61 eV and high critical temperature of 387 and 447 K, respectively. The residual unpaired p electrons on the S anions lead to a strong direct-exchange interaction between the Cr and S atoms. Moreover, their room-temperature magnetism is robust under biaxial strain, while the bandgap can be remarkably modulated with strain. The novel magnetic properties in 2D Cr2X3S3 Janus magnetic semiconductors give them promising applications in spintronics.