Electronic structure of single-crystalline Sr(Fe1xCox)2As2 probed by x-ray absorption spectroscopy: Evidence for effectively isovalent substitution of Fe2+ by Co2+

M. Merz, F. Eilers, Th. Wolf, P. Nagel, H. v. Löhneysen, and S. Schuppler
Phys. Rev. B 86, 104503 – Published 4 September 2012

Abstract

The substitutional dependence of valence and spin-state configurations of Sr(Fe1xCox)2As2 (x=0, 0.05, 0.11, 0.17, and 0.38) is investigated with near-edge x-ray absorption fine structure at the L2,3 edges of Fe, Co, and As. The present data provide direct spectroscopic evidence for an effectively isovalent substitution of Fe2+ by Co2+, which is in contrast to the widely assumed Co-induced electron-doping effect. Moreover, the data reveal that not only does the Fe valency remain completely unaffected across the entire doping range, but so do the Co and As valencies as well. The data underline a prominent role of the hybridization between (Fe,Co) 3dxy, dxz, dyz orbitals and As 4s/4p states for the band structure in A(Fe1xCox)2As2 and suggest that the covalency of the (Fe,Co)-As bond is a key parameter for the interplay between magnetism and superconductivity.

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  • Received 20 October 2011

DOI:https://doi.org/10.1103/PhysRevB.86.104503

©2012 American Physical Society

Authors & Affiliations

M. Merz1,*, F. Eilers1,2, Th. Wolf1, P. Nagel1, H. v. Löhneysen1,3, and S. Schuppler1

  • 1Institut für Festkörperphysik, Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany
  • 2Fakultät für Physik, Karlsruhe Institute of Technology, 76031 Karlsruhe, Germany
  • 3Physikalisches Institut, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany

  • *Corresponding author: michael.merz@kit.edu

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Vol. 86, Iss. 10 — 1 September 2012

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