Intrinsic half-metallicity in two-dimensional CrTeX (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 CrTeX (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 CrTeX monolayers with half-metallicity. The Curie temperatures from Monte Carlo simulations are 486, 445, and 451 K for CrTeI, CrTeBr, and CrTeCl 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 CrTeX monolayers, in which the easy axes are along the plane for the CrTeBr and CrTeCl monolayers, but being out of the plane in the CrTeI. Our study implies the potential application of the 2D CrTeX (X = I, Br, Cl) monolayers in spin nanodevices.