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.