Half-metallicity of bulk and (111) surface for full-Heusler alloy Co2VAl: A density functional study

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 mu(B) per formula unit is confirmed in the bulk Co2VAl with L2(1) 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. (C) 2013 Elsevier B.V. All rights reserved.