Bulk and surface half-metallicity of CsS in CsCl structure: A density functional theory study

Abstract

Abstract The electronic and magnetic properties of CsS in CsCl structure have been investigated. Comparisons between the total energies of CsS in different structures such as CsCl, zinc-blende, rocksalt, wurtzite and NiAs show that the CsCl structure is the most stable. Also we have done the full relaxation of atomic positions and cell parameters and we find out that CsCl with lattice parameter of 4.24 A is the most stable structure of CsS. According to our calculation in GGA approximation, CsS in CsCl structure is a half-metallic ferromagnet with a magnetic moment of 1 μ B per formula unit and half-metallic gap of 0.4 eV. We also consider CsS under stress and it is found that it preserves the half-metallicity up to lattice compression of 40%. The electronic and magnetic properties of (0 0 1), (1 1 0) and (1 1 1) surfaces of CsS in CsCl structure are also studied to find the robustness of half-metallicity at the surface. We find out that the half-metallicity of bulk CsS is lost only in Cs-terminated (0 0 1) surface but it is preserved in all of the other surfaces. In addition, we study the properties of CsS in GGA + U approximation and we realize that it is still a half-metal with a larger half-metallic gap of 1.76 eV. Finally, the Curie temperature is estimated in mean field approximation and it is found to be much more than the room temperature. All of the above properties cause the CsS compound to be a promising candidate for spintronic applications.