Evolution of Eu valence and superconductivity in layered Eu0.5La0.5FBiS2−xSex system
Y. Mizuguchi, E. Paris, T. Wakita, G. Jinno, A. Puri, K. Terashima, B. Joseph, O. Miura, T. Yokoya, N. L. Saini
DOI 10.1103/PhysRevB.95.064515 · Physical Review B
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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.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Eu0.5La0.5FBiS2-xSex Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| Eu0.5La0.5FBiS2-xSex Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | — | Pressure not reported | unknown |
| LaO1-xFxBiS2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 10 | Pressure not reported | unknown |
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