Disorder-driven electronic localization and phase separation in superconducting Fe1+yTe0.5Se0.5 single crystals
S. Rößler, Dona Cherian, S. Harikrishnan, H. L. Bhat, Suja Elizabeth, J. A. Mydosh, L. H. Tjeng, F. Steglich, S. Wirth
DOI 10.1103/PhysRevB.82.144523 · Physical Review B
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Abstract
We have investigated the influence of Fe excess on the electrical transport and magnetism of Fe1+yTe0.5Se0.5 (y=0.04 and 0.09) single crystals. Both compositions exhibit resistively determined superconducting transitions (Tc) with an onset temperature of about 15 K. From the width of the superconducting transition and the magnitude of the lower critical field Hc1, it is inferred that excess of Fe suppresses superconductivity. The linear and nonlinear responses of the ac susceptibility show that the superconducting state for these compositions is inhomogeneous. A possible origin of this phase separation is a magnetic coupling between Fe excess occupying interstitial sites in the chalcogen planes and those in the Fe-square lattice. The temperature derivative of the resistivity dρ/dT in the temperature range Tc<T<Ta with Ta being the temperature of a magnetic anomaly, changes from positive to negative with increasing Fe. A log 1/T divergence of the resistivity above Tc in the sample with higher amount of Fe suggests a disorder-driven electronic localization.
Source-reported materials — not catalogue approval
| Formula | Reported Tc (K) | Pressure (GPa) | Type |
|---|---|---|---|
| Fe1.09Te0.55Se0.45 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 15 | Pressure not reported | onset |
| Fe1.09Te0.55Se0.45 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 15 | Pressure not reported | onset |
| Fe1.04Te0.52Se0.48 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 15 | Pressure not reported | onset |
| Fe1.04Te0.52Se0.48 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 15 | Pressure not reported | onset |
| FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 8.5 | Pressure unresolved | unknown |
| FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula. | 37 | Pressure not reported | unknown |
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