Electronic and Magnetic Properties of the Bulk and Surfaces of Rock salt KM (M = Se and Te): A Density Functional Theory Study

Electronic and magnetic properties of the bulk and different surfaces of KM (M = Se and Te) in rock salt structure (rs-KM) have been investigated. The results of our calculations show that these compounds are half-metallic ferromagnets with a magnetic moment of 1 mu (B). The origin of half-metallicity is also considered by plotting the partial densities of states (DOSs) and the spin-dependent band structures. The Curie temperatures of the samples are found to be 541 and 386 K for KSe and KTe, respectively. We also find that these compounds can preserve the half-metallicity up to high lattice compressions which means that they could be grown over several semiconductors. The results of the calculations show that the bulk half-metallicity is well preserved at all of the (001), (110), K-terminated (111), and M-terminated (111) surfaces. Using ab initio atomic thermodynamics, we calculate the surface energy as a function of chemical potential to find the most stable surface and we find that the K-terminated (111) surface is the most stable surface over the whole allowed range of the chemical potential.