Surface effects on the magnetic properties of Co2FeAl(001): An ab initio study

Abstract Electronic structures of the Co 2 FeAl(0 0 1) surface are studied theoretically via first-principles calculations based on density functional theory. It is found that the minority spin band gap at the Fermi level in bulk Co 2 FeAl disappears at the surface due to space localization of the states. However, beneath the surface, the density of states of individual atoms shows a trend of minority spin gap opening at the Fermi level, which indicates that the electronic structures become close to that of bulk Co 2 FeAl. The termination of FeAl is more favorable for spin polarization of Co 2 FeAl films than that of Co. Accordingly, we present a composite tri-layer model to illustrate the fading of the half-metallic property in Co 2 FeAl films against the ideal character in bulk materials.