Charge doping and electric field tunable ferromagnetism and Curie temperature of the MnS₂ monolayer

Two-dimensional ferromagnets with a long-range ferromagnetic ordering at finite temperature present a bright prospect for their potential applications in nanoscale spintronic devices. The tuning of their intrinsic ferromagnetism and Curie temperature is essential for the development of next-generation data storage and spintronic devices. In this work, the electronic structures, ferromagnetism and Curie temperature of two-dimensional MnS₂ monolayer are controlled by charge doping and electric field using first principles calculations. The results show that the dynamic and thermal stability of monolayer MnS₂ for all of the cases can be still maintained. Moreover, there is no existence of phase transition and all MnS₂ monolayers at any charge doping concentrations and electric field intensities favor ferromagnetic coupling. For the manipulation of electron doping, the calculated total magnetic moment M_tot of the MnS₂ monolayer exhibits an increase from 3.112 to 3.491μ_B per unit cell. Further analysis indicates that a transition from half-metal to metal occurs by introducing the charge doping and vertical electric field, and the Mn 3d electronic states are the major determinants of ferromagnetism. Additionally, the charge doping enables the magnetic anisotropy energy to transform from an in-plane easy axis to the magnetization direction out of the plane. The Curie temperature T_c of the MnS₂ monolayer can be moderately enhanced above room temperature by hole doping and application of a vertical electric field. Remarkably, T_c reaches its peak at 767 K at a hole doping concentration of -0.8e. This work enriches the microscopic understanding of the tuning mechanism of ferromagnetism and supplies a sound theoretical basis for subsequent experimental studies.