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Title: Comparative thermal-expansion study of {beta}"-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}-(ET){sub 2}Cu(NCS){sub 2} : uniaxial pressure coeffcients of T{sub c} and upper critical fields.

Abstract

We report high-resolution measurements of the coefficient of thermal expansion, {alpha}=l{sup -1}x({partial_derivative}l/{partial_derivative}T), on single crystals of the organic superconductors {beta}'-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}-(ET){sub 2}Cu(NCS){sub 2}. For both salts we find large and highly anisotropic phase-transition anomalies at T{sub c}. Combining these data with literature results on the specific heat via the Ehrenfest relation, the uniaxial pressure coefficients of T{sub c} can be determined. Most remarkably, a strikingly similar in-plane vs out-of-plane anisotropy is found for both compounds: the strong suppression of T{sub c} observed in hydrostatic-pressure experiments is dominated by a huge negative uniaxial stress effect perpendicular to the conducting planes. Therefore we expect that an increase of T{sub c} in this class of superconductors can be obtained by enlarging the distance between the conducting layers. Application of magnetic fields perpendicular to the planes for the {beta}''-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} salt were found to result in pronounced superconducting fluctuation effects and scaling behavior in {alpha}(T,B). Owing to the pronounced phase-transition anomalies in {alpha}(T,B) at T{sub c}, our measurements allow for an accurate determination of the upper critical fields. We find B{sub c{sub 2}}{sup {perpendicular}}(0)=(1.4{+-}0.2)T and B{sub c{sub 2}}{sup {parallel}}(0)=(10.4{+-}0.5)T for fields perpendicular and parallelmore » to the conducting planes, respectively.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
942657
Report Number(s):
ANL/CHM/JA-33530
Journal ID: ISSN 1098-0121; TRN: US200920%%107
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Phys. Rev. B
Additional Journal Information:
Journal Volume: 61; Journal Issue: 17 ; May 1, 2000; Journal ID: ISSN 1098-0121
Country of Publication:
United States
Language:
ENGLISH
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRITICAL FIELD; MAGNETIC FIELDS; MONOCRYSTALS; ORGANIC SUPERCONDUCTORS; PRESSURE COEFFICIENT; SPECIFIC HEAT; THERMAL EXPANSION

Citation Formats

Muller, J., Lang, M., Steglich, F., Schlueter, J. A., Kini, A. M., Geiser, U., Nixon, P. G., Winter, R. W., Gard, G. L., Sasaki, T., Toyota, N., Max-Planck Inst. for Chemical Physics of Solids, Portland State Univ., and Tohoku Univ. Comparative thermal-expansion study of {beta}"-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}-(ET){sub 2}Cu(NCS){sub 2} : uniaxial pressure coeffcients of T{sub c} and upper critical fields.. United States: N. p., 2000. Web. doi:10.1103/PhysRevB.61.11739.
Muller, J., Lang, M., Steglich, F., Schlueter, J. A., Kini, A. M., Geiser, U., Nixon, P. G., Winter, R. W., Gard, G. L., Sasaki, T., Toyota, N., Max-Planck Inst. for Chemical Physics of Solids, Portland State Univ., & Tohoku Univ. Comparative thermal-expansion study of {beta}"-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}-(ET){sub 2}Cu(NCS){sub 2} : uniaxial pressure coeffcients of T{sub c} and upper critical fields.. United States. doi:10.1103/PhysRevB.61.11739.
Muller, J., Lang, M., Steglich, F., Schlueter, J. A., Kini, A. M., Geiser, U., Nixon, P. G., Winter, R. W., Gard, G. L., Sasaki, T., Toyota, N., Max-Planck Inst. for Chemical Physics of Solids, Portland State Univ., and Tohoku Univ. Mon . "Comparative thermal-expansion study of {beta}"-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}-(ET){sub 2}Cu(NCS){sub 2} : uniaxial pressure coeffcients of T{sub c} and upper critical fields.". United States. doi:10.1103/PhysRevB.61.11739.
@article{osti_942657,
title = {Comparative thermal-expansion study of {beta}"-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}-(ET){sub 2}Cu(NCS){sub 2} : uniaxial pressure coeffcients of T{sub c} and upper critical fields.},
author = {Muller, J. and Lang, M. and Steglich, F. and Schlueter, J. A. and Kini, A. M. and Geiser, U. and Nixon, P. G. and Winter, R. W. and Gard, G. L. and Sasaki, T. and Toyota, N. and Max-Planck Inst. for Chemical Physics of Solids and Portland State Univ. and Tohoku Univ.},
abstractNote = {We report high-resolution measurements of the coefficient of thermal expansion, {alpha}=l{sup -1}x({partial_derivative}l/{partial_derivative}T), on single crystals of the organic superconductors {beta}'-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} and {kappa}-(ET){sub 2}Cu(NCS){sub 2}. For both salts we find large and highly anisotropic phase-transition anomalies at T{sub c}. Combining these data with literature results on the specific heat via the Ehrenfest relation, the uniaxial pressure coefficients of T{sub c} can be determined. Most remarkably, a strikingly similar in-plane vs out-of-plane anisotropy is found for both compounds: the strong suppression of T{sub c} observed in hydrostatic-pressure experiments is dominated by a huge negative uniaxial stress effect perpendicular to the conducting planes. Therefore we expect that an increase of T{sub c} in this class of superconductors can be obtained by enlarging the distance between the conducting layers. Application of magnetic fields perpendicular to the planes for the {beta}''-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} salt were found to result in pronounced superconducting fluctuation effects and scaling behavior in {alpha}(T,B). Owing to the pronounced phase-transition anomalies in {alpha}(T,B) at T{sub c}, our measurements allow for an accurate determination of the upper critical fields. We find B{sub c{sub 2}}{sup {perpendicular}}(0)=(1.4{+-}0.2)T and B{sub c{sub 2}}{sup {parallel}}(0)=(10.4{+-}0.5)T for fields perpendicular and parallel to the conducting planes, respectively.},
doi = {10.1103/PhysRevB.61.11739},
journal = {Phys. Rev. B},
issn = {1098-0121},
number = 17 ; May 1, 2000,
volume = 61,
place = {United States},
year = {2000},
month = {5}
}