First-principles investigation of the structural and electronic properties of bulk full-Heusler alloy Mn2CoSn and its (0 0 1) surface

• The bulk Mn2CoSn Heusler alloy is found to be a half-metallic ferrimagnet.
• The half-metallicity confirmed in the bulk Mn2CoSn is destroyed at the (0 0 1) surfaces.
• The spin state of Mn(1) atom is turned from low-spin state to high-spin state.
• The full-Heusler alloy displays a Slater-Pauling demeanor.

In this paper, the first-principles calculations have been performed to study the electronic and magnetic properties of the bulk and (0 0 1) surface of Mn2CoSn. The bulk Mn2CoSn Heusler alloy is found to be a half-metallic ferrimagnet with a total magnetic moment of 3.0 μB per formula unit at the equilibrium lattice constant of 5.85 Ǻ. The full-Heusler alloy displays a Slater-Pauling demeanor and the total magnetic moment (Mtot) with the total number of valence electrons (Ztot  ) complying the rule Mtot=(Ztot-24)Mtot=(Ztot-24). Investigating the electronic density of states, we discover that the half-metallicity confirmed in the bulk Mn2CoSn is destroyed at both the Mn(2)Sn- and Mn(1)Co-terminated (0 0 1) surfaces. Moreover, we find the atomic magnetic moments at the Mn(2)Sn-terminated (0 0 1) surface are increased compared to those of the bulk Mn2CoSn, while they increase at the Mn(1)Co-terminated (0 0 1) surface. Interestingly, the spin state of Mn(1) atom is turned from low-spin state to high-spin state at the Mn(1)Co-terminated (0 0 1) surface, which makes Mn2CoSn full-Heusler alloy a promising candidate for spintronic applications.