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Title: Method for accurate determination of the electron contribution: Specific heat of Ba 0.59K 0.41Fe 2As 2

Abstract

Twenty two years after the opening of the field of high temperature superconductivity by Georg Bednorz and Alex Müller a new addition to this class of materials, namely the iron-pnictides and chalcogenides, perplexes the scientific community. Making use of the accumulated wisdom, a great deal of their physics has been “mapped” in record time using all available measurement techniques. Among these, specific-heat has been proven a powerful and unique technique in the study of physical properties of bulk materials, especially of superconductors. We report here specific-heat measurements on the nearly optimally doped iconic iron-arsenide superconductor Ba 0.59K 0.41Fe 2As 2. We use a new method, based on direct comparisons of α-model expressions for the electron contribution with the measured total specific heat, to extract the electron contribution. It circumvents the need in the conventional analyses for an independent, necessarily approximate, determination of the lattice contribution, which is subtracted from the total to obtain the electron contribution, and it eliminates the consequent uncertainties in the electron contribution. For Ba 0.59K 0.41Fe 2As 2 the electron density of states is comprised of contributions from two electron bands with superconducting-state energy gaps differing by a factor 3.8, with 77% coming from the bandmore » with the larger gap. The vortex-state specific heat suggests nodeless gaps. Comparison of the normal-state density of states with band-structure calculations shows an extraordinarily large effective mass enhancement, for which there is no precedent in simple metals and no theoretical explanation.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1466701
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Book
Resource Relation:
Journal Name: Springer Series in Materials Science; Journal Volume: 255; Related Information: © 2017, Springer International Publishing AG.
Country of Publication:
United States
Language:
English

Citation Formats

Rotundu, CR, Forrest, TR, Phillips, NE, and Birgeneau, RJ. Method for accurate determination of the electron contribution: Specific heat of Ba0.59K0.41Fe2As2. United States: N. p., 2017. Web. doi:10.1007/978-3-319-52675-1_23.
Rotundu, CR, Forrest, TR, Phillips, NE, & Birgeneau, RJ. Method for accurate determination of the electron contribution: Specific heat of Ba0.59K0.41Fe2As2. United States. doi:10.1007/978-3-319-52675-1_23.
Rotundu, CR, Forrest, TR, Phillips, NE, and Birgeneau, RJ. Wed . "Method for accurate determination of the electron contribution: Specific heat of Ba0.59K0.41Fe2As2". United States. doi:10.1007/978-3-319-52675-1_23. https://www.osti.gov/servlets/purl/1466701.
@article{osti_1466701,
title = {Method for accurate determination of the electron contribution: Specific heat of Ba0.59K0.41Fe2As2},
author = {Rotundu, CR and Forrest, TR and Phillips, NE and Birgeneau, RJ},
abstractNote = {Twenty two years after the opening of the field of high temperature superconductivity by Georg Bednorz and Alex Müller a new addition to this class of materials, namely the iron-pnictides and chalcogenides, perplexes the scientific community. Making use of the accumulated wisdom, a great deal of their physics has been “mapped” in record time using all available measurement techniques. Among these, specific-heat has been proven a powerful and unique technique in the study of physical properties of bulk materials, especially of superconductors. We report here specific-heat measurements on the nearly optimally doped iconic iron-arsenide superconductor Ba0.59K0.41Fe2As2. We use a new method, based on direct comparisons of α-model expressions for the electron contribution with the measured total specific heat, to extract the electron contribution. It circumvents the need in the conventional analyses for an independent, necessarily approximate, determination of the lattice contribution, which is subtracted from the total to obtain the electron contribution, and it eliminates the consequent uncertainties in the electron contribution. For Ba0.59K0.41Fe2As2 the electron density of states is comprised of contributions from two electron bands with superconducting-state energy gaps differing by a factor 3.8, with 77% coming from the band with the larger gap. The vortex-state specific heat suggests nodeless gaps. Comparison of the normal-state density of states with band-structure calculations shows an extraordinarily large effective mass enhancement, for which there is no precedent in simple metals and no theoretical explanation.},
doi = {10.1007/978-3-319-52675-1_23},
journal = {Springer Series in Materials Science},
number = ,
volume = 255,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}

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