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RESEARCH PRODUCT
Charge transfer and tunable minority band gap at the Fermi energy of a quaternaryCo2(MnxTi1−x)GeHeusler alloy
C. G. F. BlumBenjamin BalkeM. KallmayerGerhard H. FecherP. KlaerClaudia FelserT. BosJoachim BarthTanja GrafH. J. Elmerssubject
Materials scienceMagnetic momentCondensed matter physicsBand gapFermi levelFermi energyCondensed Matter PhysicsSemimetalElectronic Optical and Magnetic MaterialsCondensed Matter::Materials Sciencesymbols.namesakeMagnetizationsymbolsDensity of statesDirect and indirect band gapsAtomic physicsdescription
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 ${\text{Co}}_{2}({\text{Mn}}_{x}{\text{Ti}}_{1\ensuremath{-}x})\text{Ge}$ 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.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2010-09-09 | Physical Review B |