Magnetic properties of a ferromagnetic Heusler alloy Co2MnSn

The electronic and magnetic properties of the MnSn terminated (001) surfaces of the ferromagnetic full-Heusler alloy Co2MnSn with half-metallic character are investigated theoretically by using the all-electron full-potential linearized augmented plane wave (FLAPW) method within the generalized gradient approximation (GGA) for exchange and correlation. The calculated magnetic moment for surface Mn (3.68 mu(B)) exhibits much enhanced value compared with the bulk moment (3.17 mu(B)). We can see that the MnSn terminated surface also affects the Co magnetic moment on the subsurface layer (1.10 mu(B)) to be slightly larger than the bulk value (0.98 mu(B)). The local magnetic moment on the Sn site couples antiferromagnetically to Mn moment with a very small value (less than 0.1 mu(B)). The calculated density of states (DOS) shows that there is a very small finite spin-down DOS at the Fermi level instead of a band gap for the Mn surface layer, which indicates that the half-metallicity may be destroyed by surface states for the MnSn teminated surface. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.