High-temperature ferromagnetic semiconductors: Janus monolayer vanadium trihalides
Yulu Ren, Qiaoqiao Li, Wenhui Wan, Yong Liu, Yanfeng Ge
Abstract
Two-dimensional intrinsic ferromagnetic semiconductors are expected to stand out in the spintronic field. Recently, monolayer ${\mathrm{VI}}_{3}$ was experimentally synthesized, but the weak ferromagnetism and low Curie temperature ${T}_{C}$ limit its potential application. Here we report that the Janus structure can elevate ${T}_{C}$ to 240 K. And we discuss the reason for high ${T}_{C}$ in the Janus structure, which is the lower virtual exchange gap between ${t}_{2g}$ and ${e}_{g}$ states of nearest-neighbor V atoms. In addition, ${T}_{C}$ can be further substantially enhanced by tensile strain due to the increasing ferromagnetism driven by rapidly quenched direct exchange interaction. Our work supports a feasible approach to enhance Curie temperature of monolayer ${\mathrm{VI}}_{3}$ and unveils stable intrinsic FM semiconductors for realistic applications in spintronics.