Janus V 2 AsP monolayer : a ferromagnetic semiconductor with a narrow band gap, a high Curie temperature and controllable magnetic anisotropy.

The search and design of two-dimensional (2D) magnetic semiconductors for spintronics applications are particularly significant. In this work, we investigated the electronic and magnetic properties of Janus structure based on Dirac half-metallic VP monolayer by first-principles calculations. Due to the vertical symmetry breaking, Janus V 2 AsP monolayer becomes an intrinsic ferromagnetic semiconductor with a narrow band gap of 0.21 eV. We analyzed the electronic structure and origin of the in-plane easy axis in Janus V 2 AsP. The electron effective mass is anisotropic and only 0.129 m 0 along the x-direction. The Curie temperature T c and magnetic anisotropy energy (MAE) of Janus V 2 AsP reach 490 K and 178 µeV per V atom, respectively. A uniaxial tensile stain ε x of 5% can increase its band gap and MAE to 0.39 eV and 210.6 µeV per V atom while maintaining its Tc being above room temperature. Moreover, the direction of the easy axis can be changed between the in-plane x- and y-direction by a small uniaxial tensile strain ε x of 2%. Our study can motivate further research on the design the magnetic semiconductors in Janus structures based on 2D Dirac half-metals for spintronics applications.