Enhanced ferromagnetism, magnetic anisotropy, and spin polarization in Janus CrSeTe via strain and doping

Recently, experimental 2D magnetic CrSe2 and CrTe2 inspired the study on their Janus CrSeTe, which breaks the mirror symmetry of Cr–Se(Te)–Cr. However, the CrSeTe monolayer possesses a lower Curie temperature and the in-plane magnetic anisotropy, and few works concerned both its zigzag- and stripy-antiferromagnetic states, which are crucial to determine the magnetic ground state and magnetic transition temperature. In this Letter, using first-principles calculations and Monte Carlo simulations, we systematically explore the strain, carrier-doping, and electric field effects on magnetic and electronic properties of monolayer CrSeTe. We demonstrate that monolayer CrSeTe preserves ferromagnetism in a large range of whether strain or doping. The estimated Curie temperature can be increased from 167 K to the room-temperature by the combination of 4% tensile strain and 0.1 e doping due to the enhanced ferromagnetic Cr–Se(Te)–Cr super-exchange interaction. Interestingly, either a small tensile strain (1%) or a low hole doping (0.025 h) can induce the transition of the easy axis from in-plane to out-of-plane due to the increased out-of-plane magnetic anisotropy from hybridized pz and py orbitals of Te atoms. In addition, the spin polarization is improved by over 60% by the tensile strain. Our results suggest that small strain and low carrier-doping induced room-temperature ferromagnetism, large out-of-plane magnetic anisotropy, and high spin polarization make CrSeTe useful in 2D spintronic applications and will stimulate broad studies on the regulation of magnetic and electronic properties of this class of magnetic Janus monolayers.