Intrinsic half-metallicity in two-dimensional Cr₂TeX₂ (X = I, Br, Cl) monolayers

Two-dimensional (2D) materials with intrinsic half-metallicity at or above room temperature are important in spin nanodevices. Nevertheless, such 2D materials in experiment are still rarely realized. In this work, a new family of 2D Cr₂TeX₂ (X = I, Br, Cl) monolayers has been predicted using first-principles calculations. The monolayer is made of five atomic sublayers with ABCAB-type stacking along the perpendicular direction. It is found that the energies for all the ferromagnetic (FM) half-metallic states are the lowest. The phonon spectrum calculations and molecular dynamics simulations both demonstrate that the FM states are stable, indicating the possibility of experimentally obtaining the 2D Cr₂TeX₂ monolayers with half-metallicity. The Curie temperatures from Monte Carlo simulations are 486, 445, and 451 K for Cr₂TeI₂, Cr₂TeBr₂, and Cr₂TeCl₂ monolayers, respectively, and their half-metallic bandgaps are 1.72, 1.86 and 1.90 eV. The corresponding magnetocrystalline anisotropy energies (MAEs) are about 1185, 502, 899 μeV per Cr atom for Cr₂TeX₂ monolayers, in which the easy axes are along the plane for the Cr₂TeBr₂ and Cr₂TeCl₂ monolayers, but being out of the plane in the Cr₂TeI₂. Our study implies the potential application of the 2D Cr₂TeX₂ (X = I, Br, Cl) monolayers in spin nanodevices.