First-Principles Studies on d 0 Magnetism in Zinc-Blende IV-IV Compounds-Based Short-Period Heterostructures (SiC)1/(KC)1, (GeC)1/(KC)1, (SiC)1/(CaC)1, and (GeC)1/(CaC)1

Abstract

With extensive first-principle calculations based on density functional theory, short-period heterostructures based on zinc-blende SiC and GeC exhibiting d 0 magnetism were modeled and simulated. The results implied that the heterostructures should be orbital-resolved hole-induced magnetic materials, in which the magnetism is driven by 2p partially filled states. Our results showed the similarities and the differences in electronic structures (electron occupation) and magnetic properties (spin configuration) between the XC (X = K and Ca) and (MC)1/(XC)1 (001) (M = Si and Ge; X = K and Ca). By adding Coulomb force, the metal to half-metal and half-metal to semiconductor transitions were found in K- and Ca-embedded heterostructures, respectively. Moreover, the results confirmed that the coexistence of covalency and half metallicity was critical for the existence of the spin-resolved pseudogap and the pseudogap formation was important for the real forbidden gap opening. The similarities and differences of electronic structures and magnetic properties between (MC)1/(KC)1 and (MC)1/(CaC)1 were analyzed by lattice symmetry and orbital occupation. In addition, to predict the structural stability, these heterostructures were computed upon tetragonal, orthorhombic, and rhombohedral deformations and these compounds are found to be energetically stable against these three lattice deformations.