1. Probing the electronic states of high-TMR off-stoichiometric Co2MnSI thin films by hard x-ray photoelectron spectroscopy.
- Author
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Kozina, Xeniya, Karel, Julie, Ouardi, Siham, Chadov, Stanislav, Fecher, Gerhard H., Felser, Claudia, Stryganyuk, Gregory, Balke, Benjamin, Ishikawa, Takayuki, Uemura, Tetsuya, Yamamoto, Masafumi, Ikenaga, Eiji, Ueda, Shigenori, and Kobayashi, Keisuke
- Subjects
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TUNNEL magnetoresistance , *ELECTRONIC structure , *MAGNETIC tunnelling , *FERROMAGNETIC materials , *BAND gaps , *X-ray photoelectron spectroscopy - Abstract
The tunnel magnetoresistance ratio (TMR) of fully epitaxial magnetic tunnel junctions with an off- stoichiometric Co2MnSi Heusler alloy has been shown to exhibit a systematic dependence on Mn content, reaching 1135% at 4.2 K for Co2Mn1.29Si. In this paper, we explain the behaviorof the observed TMR ratio using ab initio calculations and hard x-ray photoelectron spectroscopy (HAXPES). For the Mn-deficient samples, we show that the the drop of the TMR is caused by Co antisite atoms, which impose extra states into the minority-spin band gap. On the other hand, Mn-excess composition shows nearly half-metallic behavior. This result can be intuitively understood since both Co2MnSi and Mn2CoSi are theoretically predicted to be half-metallic ferromagnets. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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