Two dimensional CrGa₂Se₄: a spin-gapless ferromagnetic semiconductor with inclined uniaxial anisotropy

Magnetic semiconductors with high critical temperature have long been the focus in materials science and are also known as one of the fundamental questions in two-dimensional (2D) materials. Based on density functional theory calculations, we predict a 2D spin-gapless ferromagnetic semiconductor of CrGa₂Se₄ monolayer, in which the type of spin-polarized current can be tuned by tailoring the Fermi energy. Moreover, the magnetic anisotropy energy calculations indicate that the CrGa₂Se₄ monolayer possesses spin anisotropy both in the basal plane and the vertical plane. This originates from the distortion-induced rearrangement of the 3d electrons in the CrSe₆ octahedron and results in an inclined easy axis out of the film. The Curie temperature (T_c) of ferromagnetic phase transition for 2D CrGa₂Se₄ is more than 200 K. This 2D material shows promising transport properties for spintronics applications and is also important for fundamental research in 2D magnetism.