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The origin of anisotropy and high density of states in the electronic structure of Cr2GeC by means of polarized soft X-ray spectroscopy and ab initio calculations

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Magnuson, Martin and Mattesini, Maurizio and Bugnet, Matthieu and Eklund, Per (2015) The origin of anisotropy and high density of states in the electronic structure of Cr2GeC by means of polarized soft X-ray spectroscopy and ab initio calculations. Journal of physics: Condensed matter, 27 (41). p. 415501. ISSN 0953-8984

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Official URL: http://dx.doi.org/10.1088/0953-8984/27/41/415501


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Abstract

The anisotropy in the electronic structure of the inherently nanolaminated ternary phase Cr2GeC is investigated by bulk-sensitive and element selective soft x-ray absorption/emission spectroscopy. The angle-resolved absorption/emission measurements reveal differences between the in-plane and out-of-plane bonding at the (0001) interfaces of Cr2GeC. The Cr L 2, 3, C K, and Ge M 1, M 2, 3 emission spectra are interpreted with first-principles density-functional theory (DFT) including core-to-valence dipole transition matrix elements. For the Ge 4s states, the x-ray emission measurements reveal two orders of magnitude higher intensity at the Fermi level than DFT within the General Gradient Approximation (GGA) predicts. We provide direct evidence of anisotropy in the electronic structure and the orbital occupation that should affect the thermal expansion coefficient and transport properties. As shown in this work, hybridization and redistribution of intensity from the shallow 3d core levels to the 4s valence band explain the large Ge density of states at the Fermi level.


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© 2015 IOP Publishing Ltd.
We thank the staff at MAX IV Laboratory for experimental support as well as M Jaouen and V Mauchamp for discussions. This work was financially supported by the Swedish Research Council Linnaeus Grant LiLi-NFM and the Swedish Foundation for Strategic Research (SSF) through the Synergy Grant FUNCASE and Future Research Leaders 5 Program. PE also acknowledges the University of Poitiers for a Visiting. Professor position. M Mattesini acknowledges financial support by the Spanish Ministry of Economy and Competitiveness (CGL 2013-41860-P) and by the BBVA Foundation.

Uncontrolled Keywords:MAX-phases; Nanolaminates; Soft x-ray spectroscopy; Electronic structure; Density functional theory
Subjects:Sciences > Physics > Solid state physics
ID Code:33395
Deposited On:30 Sep 2015 18:23
Last Modified:28 Sep 2016 23:01

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