Evolution of Eu valence and superconductivity in layered Eu0.5La0.5FBiS2-xSex system

Y. Mizuguchi, E. Paris, T. Wakita, G. Jinno, A. Puri, Kensei Terashima, B. Joseph, O. Miura, T. Yokoya, N. L. Saini

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16 Citations (Scopus)


We have studied the effect of Se substitution on Eu valence in a layered Eu0.5La0.5FBiS2-xSex superconductor using a combined analysis of x-ray absorption near-edge structure (XANES) and x-ray photoelectron spectroscopy (XPS) measurements. Eu L3-edge XANES spectra reveal that Eu is in the mixed valence state with coexisting Eu2+ and Eu3+. The average Eu valence decreases sharply from ∼2.3 for x=0.0 to ∼2.1 for x=0.4. Consistently, Eu 3d XPS shows a clear decrease in the average valence by Se substitution. Bi 4f XPS indicates that effective charge carriers in the BiCh2 (Ch = S, Se) layers are slightly increased by Se substitution. On the basis of the present results it has been discussed that the metallic character induced by Se substitution in Eu0.5La0.5FBiS2-xSex is likely to be due to increased in-plane orbital overlap driven by reduced in-plane disorder that affects the carrier mobility.

Original languageEnglish
Article number064515
JournalPhysical Review B
Issue number6
Publication statusPublished - Feb 27 2017

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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