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Title: Evolution of correlation strength in K x Fe 2 y Se 2 superconductor doped with S

Abstract

We report the evolution of thermal transport properties of K x Fe 2 – y Se 2 with sulfur substitution at Se sites. Sulfur doping suppresses the superconducting T 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 μ V/K 2 to a very small value, ~ 0.03 μ V/K 2 , where T c is completely suppressed. The normal-state electron Sommerfeld term ( γ n ) of specific heat also decreases with the increase in sulfur content. The decrease of S / T and γ 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.

Authors:
; ;
Publication Date:
Research Org.:
Energy Frontier Research Centers (EFRC) (United States). Center for Emergent Superconductivity (CES)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1385598
DOE Contract Number:  
AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 84; Journal Issue: 5; Related Information: CES partners with Brookhaven National Laboratory (BNL); Argonne National Laboratory; University of Illinois, Urbana-Champaign; Los Alamos National Laboratory; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; phonons, thermal conductivity, energy storage (including batteries and capacitors), superconductivity, defects, spin dynamics

Citation Formats

Wang, Kefeng, Lei, Hechang, and Petrovic, C. Evolution of correlation strength in K x Fe 2–y Se 2 superconductor doped with S. United States: N. p., 2011. Web. doi:10.1103/PhysRevB.84.054526.
Wang, Kefeng, Lei, Hechang, & Petrovic, C. Evolution of correlation strength in K x Fe 2–y Se 2 superconductor doped with S. United States. https://doi.org/10.1103/PhysRevB.84.054526
Wang, Kefeng, Lei, Hechang, and Petrovic, C. 2011. "Evolution of correlation strength in K x Fe 2–y Se 2 superconductor doped with S". United States. https://doi.org/10.1103/PhysRevB.84.054526.
@article{osti_1385598,
title = {Evolution of correlation strength in K x Fe 2–y Se 2 superconductor doped with S},
author = {Wang, Kefeng and Lei, Hechang and Petrovic, C.},
abstractNote = {We report the evolution of thermal transport properties of K x Fe 2 – y Se 2 with sulfur substitution at Se sites. Sulfur doping suppresses the superconducting T 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 μ V/K 2 to a very small value, ~ 0.03 μ V/K 2 , where T c is completely suppressed. The normal-state electron Sommerfeld term ( γ n ) of specific heat also decreases with the increase in sulfur content. The decrease of S / T and γ 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.},
doi = {10.1103/PhysRevB.84.054526},
url = {https://www.osti.gov/biblio/1385598}, journal = {Physical Review. B, Condensed Matter and Materials Physics},
issn = {1098-0121},
number = 5,
volume = 84,
place = {United States},
year = {2011},
month = {8}
}

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