Investigation of the superconducting gap structure in κ-(BEDT-TTF)2Cu(NCS)2 and κ-(BEDT-TTF)2Cu[N(CN)2]Br by means of thermal-conductivity measurements

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Contributors

  • S. Kühlmorgen - , Helmholtz-Zentrum Dresden-Rossendorf, TUD Dresden University of Technology (Author)
  • R. Schönemann - , Helmholtz-Zentrum Dresden-Rossendorf, TUD Dresden University of Technology, Florida State University (Author)
  • E. L. Green - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • J. Müller - , Goethe University Frankfurt a.M. (Author)
  • J. Wosnitza - , Chair of Physics of High Magnetic Fields, Helmholtz-Zentrum Dresden-Rossendorf (Author)

Abstract

We report temperature-dependent thermal-conductivity, κ, measurements on the layered quasi-two-dimensional organic superconductors κ-(BEDT-TTF)2Cu(NCS)2 and κ-(BEDT-TTF)2Cu[N(CN)2]Br down to 160 mK. The results for κ-(BEDT-TTF)2Cu(NCS)2 may be consistent with a nodal superconducting (SC) gap structure as indicated by a non-negligible remnant linear contribution when κ/T ∝ T2 is extrapolated to T = 0. For κ-(BEDT-TTF)2Cu[N(CN)2]Br, contrary to expectations, higher κ values are observed in the superconducting regime as compared to the normal, high-field state evidencing a dominant phonon contribution to κ in the superconducting state. The strong increase of κ in the normal state below T c for both samples indicates strong electron-phonon scattering. Our results highlight the need for thermal-conductivity measurements performed down to significantly lower temperatures to determine the symmetry of the SC gap.

Details

Original languageEnglish
Article number405604
JournalJournal of Physics Condensed Matter
Volume29
Issue number40
Publication statusPublished - 1 Sept 2017
Peer-reviewedYes

External IDs

PubMed 28748831

Keywords

ASJC Scopus subject areas

Keywords

  • organic superconductor, quasi-two dimensional, superconducting gap, thermal conductivity