Two-dimensional Janus transition-metal dichalcogenides with intrinsic ferromagnetism and half-metallicity

Searching experimental feasible two-dimensional (2D) ferromagnetic crystals with room-temperature magnetic order and high spin-polarization is one key for the development of next-generation spintronic devices. Inspired by the recent experimental achievement for the synthesis of Janus MoSSe monolayer with out-of-plane symmetry, here, by ab initio calculation, we demonstrate this feasibility with the discovery of intrinsic 2D ferromagnetic Janus TMDs monolayer (TMXX', TM = V, Cr and Mn; X, X' = S, Se and Te, X. X') with large spin-polarization and high Curie temperature. Particularly, the MnSSe monolayer show half-metal with 100% spin polarization and wide half-metallic gap. A Curie temperature as high as 400 K has been found for VSSe materials. The formation energy calculation for Janus TMDs can be comparable with the TMDs monolayer. The dynamical stability for these 2D crystals also have been confirmed by phonon spectrum calculation. Our study presents a new class of 2D magnetic materials for future spintronics and valleytronics.