Optical investigations of the superconducting energy gap in β″-(BEDT-TTF)2SF5CH2CF2SO3

Research output: Contribution to journalResearch articleContributedpeer-review


  • S. Kaiser - , University of Stuttgart (Author)
  • S. Yasin - , University of Stuttgart (Author)
  • N. Drichko - , University of Stuttgart (Author)
  • M. Dressel - , University of Stuttgart (Author)
  • T. Rõõm - , National Institute of Chemical Physics and Biophysics, Tallinn (Author)
  • D. Hüvonen - , National Institute of Chemical Physics and Biophysics, Tallinn (Author)
  • U. Nagel - , National Institute of Chemical Physics and Biophysics, Tallinn (Author)
  • G. L. Gard - , Portland State University (Author)
  • J. A. Schlueter - , Argonne National Laboratory (Author)


The organic salt β″-(BEDT-TTF)2SF5CH2CF2SO3 is a two-dimensional metal with a quarter-filled conduction band. In the metallic state the optical conductivity evidences interaction of the charge carriers with charge-order fluctuations that become stronger as temperature decreases. In the superconducting phase below Tc≈5K, indications of the superconducting gap with 2Δ≈12cm-1 are observed in the optical spectrum, corresponding to 2Δ≈/kB Tc≈3.3. Its temperature and magnetic field dependences are also consistent with predictions by the BCS theory of a weakly coupled superconductor. The conductivity ratio σ11(T = 1:75 K)/σ1(10 K) indicates the opening of the superconducting gap in β″-(BEDT-TTF)2SF5CH2CF2SO3.


Original languageEnglish
Pages (from-to)985-990
Number of pages6
JournalPhysica Status Solidi (B) Basic Research
Issue number5
Publication statusPublished - May 2012
Externally publishedYes

External IDs

ORCID /0000-0001-9862-2788/work/142255383



  • Charge order, Infrared spectroscopy, Organic conductors, Superconducting gap, THz spectroscopy