Evolution of Correlation Strength in KxFe2- ySe2 Superconductor Doped with S
We report the evolution of thermal transport properties of K{sub x}Fe{sub 2-y}Se{sub 2} with sulfur substitution at Se sites. Sulfur doping suppresses the superconducting T{sub c}. The Seebeck coefficient of all crystals in the low-temperature range can be described very well by a diffusive thermoelectric response model. The zero-temperature extrapolated value of the Seebeck coefficient divided by temperature, S/T, gradually decreases from -0.48 {mu}V/K{sup 2} to a very small value, {approx}0.03 {mu}V/K{sup 2}, where T{sub c} is completely suppressed. The normal-state electron Sommerfeld term ({gamma}{sub n}) of specific heat also decreases with the increase in sulfur content. The decrease of S/T and {gamma}{sub n} reflects a suppression of the density of states at the Fermi energy, or a change in the Fermi surface that would induce the suppression of correlation strength. Our results imply little relevance of strong electron correlations to superconductivity.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1033199
- Report Number(s):
- BNL-96342-2011-JA; R&D Project: PO-013; KC0202010; TRN: US1200299
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 84, Issue 5; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ELECTRON CORRELATION
ELECTRONS
FERMI LEVEL
SPECIFIC HEAT
SULFUR
SULFUR CONTENT
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TRANSPORT
superconductivity
thermal transport properties
sulfur doping
Seeback coefficient
normal-state electron Sommerfeld term