Tunable magnetocrystalline anisotropy and valley polarization in an intrinsic ferromagnetic Janus 2H-VTeSe monolayer

Two-dimensional Janus monolayers with specular asymmetry exhibit excellent physicochemical properties and are a good candidate for optoelectronic, valley electronic, and nanoelectronics devices. Based on the density functional theory, the Janus 2H-VTeSe monolayer is an intrinsic ferromagnetic semiconductor with an indirect band gap of 0.324 eV and exhibits a good thermodynamic and kinetic stability, in-plane magnetocrystal anisotropy, large spontaneous valley polarization of 155 meV, and high Curie temperature (T-c) of 380 K. The biaxial strain (-6% < epsilon < 6%) can effectively tune the Janus 2H-VTeSe monolayer from the bipolar magnetic semiconductor phase to half-semiconductor, spin gapless semiconductor, and half-metallic phases. Moreover, the magnetocrystal anisotropy energy (MAE) is modulated by the strain from 0.54 meV (epsilon = -6%) to 1.32 meV (epsilon = -2%), and the easy [100] and hard [001] magnetic axes could be switched from each other by charge carrier doping. The calculated valley optical response of the Janus 2H-VTeSe monolayer exhibits a valley-selective circular dichroism. Due to the broken inversion and time-reversal symmetry, the valley polarization and Berry curvature can be continuously tuned by applying biaxial strains (modulation range 24.2%), external electric field (modulation range 2%), and varying the magnetization angle (0 to 180 degrees). The Janus 2H-VTeSe monolayer possesses intrinsic ferromagnetic ordering, large spontaneous valley polarization, high T-c of 380 K, and considerable MAE of 1.15 meV, giving it a potential application in the two-dimensional spintronic devices.

Automated summary

The Janus 2H-VTeSe monolayer, as an intrinsic ferromagnetic semiconductor, exhibits excellent physicochemical properties and has potential applications in optoelectronics, valley electronics, and nanoelectronics. Its properties can be effectively tuned by biaxial strain and charge carrier doping.