Half-metallicity of bulk and (1 1 1) surface for full-Heusler alloy Co2VAl: A density functional study

•The bulk and (1 1 1) surface half-metallicity of Heusler alloy Co2VAl are investated.•The half-metallic ferromagnetism with a ground state is confirmed in bulk Co2VAl.•The bulk HM property is preserved at two surfaces but lost at other two surfaces.•The present work would be helpful for the applications of spintronic devices.

Motivated by the recent experimental synthesis of the bulk and thin films for full-Heusler alloy Co2VAl, we investigate the structural, electronic and magnetic properties of the bulk Co2VAl and its (1 1 1) surfaces based on the density functional theory. The half-metallic ferromagnetism with the magnetic moment of 2.00 μB per formula unit is confirmed in the bulk Co2VAl with L21 structure. For the four possible (1 1 1) surfaces, it is shown from the present DOS that the bulk half-metallicity is preserved at V- and Al-terminated surfaces but destroyed by some surface states at Co–V- and Co–Al-terminated surfaces. We also find that the atomic magnetic moments at the (1 1 1) surfaces are greatly different from the bulk values due to the effect of symmetry breaking at the surface. Moreover, the structure relaxation indicates that Al- and V-terminated surfaces are more favorable to the applications of spintronic devices.