Abstract
Tunneling experiments have shown that in order to retain half-metallicity at room temperature not only a large gap is required but also a Fermi energy considerably distant from the minority band edges. We correlate the position of the Fermi energy in the spin minority gap obtained from band structure calculations to Hall effect experiments. As a model system we chose Co2FexMn1-xSi, where the Fermi energy was calculated to move from the valence band edge of the minority states to the conduction band edge with increasing x. On high quality laser ablated epitaxial films we observe a sign change of both the normal and the anomalous Hall effect with doping. The experimental data agree with band structure calculations done in the LSDA + DMFT scheme. (C) 2009 Elsevier B.V. All rights reserved.