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Zusammenfassung:
We investigate the distribution of element-specific magnetic moments and changes in the spin-resolved unoccupied density of states in a series of half-metallic Co2(MnxTi1−x)Ge Heusler alloys using x-ray magnetic circular dichroism. The Co and Mn magnetic moments are oriented parallel while a small Ti moment shows antiparallel to the mean magnetization. The element-specific magnetic moments remain almost independent on the composition. Therefore, a replacement of Ti by Mn results in an increase in magnetization. The increase in magnetization with increasing x follows the Slater-Pauling rule. The Fermi level decreases with respect to the minority band gap with increasing number of valence electrons. This counterintuitive behavior is explained qualitatively by a charge transfer model and quantitatively by ab initio band-structure calculations.