@article{393f5be0a8144493b49f2938dcb54ee9,
title = "Evolution of Eu valence and superconductivity in layered Eu0.5La0.5FBiS2-xSex system",
abstract = "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.",
author = "Y. Mizuguchi and E. Paris and T. Wakita and G. Jinno and A. Puri and K. Terashima and B. Joseph and O. Miura and T. Yokoya and Saini, {N. L.}",
note = "Funding Information: We thank ESRF staff for the assistance during the measurements. Y.M. would like to acknowledge hospitality at the Sapienza University of Rome. This work was partly supported by Grants-in-Aid for Scientific Research (Grants No. 15H05886, No. 16H04493, and No. 15H03691) and the Program for Promoting the Enhancement of Research University from MEXT and the Program for Advancing Strategic International Networks to Accelerate the Circulation of Talented Researchers from JSPS. The work is part of the executive protocol of the general agreement for cooperation between the Sapienza University of Rome and Tokyo Metropolitan University and that between the Sapienza University of Rome and Okayama University. The work at Sapienza is partially supported by PRIN2012 (Grant No. 2012X3YFZ2). Publisher Copyright: {\textcopyright} 2017 American Physical Society.",
year = "2017",
month = feb,
day = "27",
doi = "10.1103/PhysRevB.95.064515",
language = "English",
volume = "95",
journal = "Physical Review B",
issn = "2469-9950",
publisher = "American Physical Society",
number = "6",
}