2001/09/03 by J. Müller, Jens Müller, Michael Lang +4
Materials Science · Physics and Astronomy · #Iron-based superconductors research #Organic and Molecular Conductors Research #Rare-earth and actinide compounds #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.65.140509
4 figures
arxiv created 2001/09/03 · openalex publication_date 2002/03/28 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We report high-resolution specific-heat measurements on the quasi-two-dimensional organic superconductor \ensuremathκ\ensuremath-(BEDT\ensuremath-TTF)2Cu(NCS)2, performed by using a sensitive ac-modulation technique. The main observations are (i) a discontinuity at Tc much in excess of what is expected for a weak-coupling BCS superconductor and (ii) a quasiparticle contribution to the specific heat with an exponentially weak temperature dependence at T\ensuremath≪Tc. The latter finding is incompatible with an order parameter that vanishes at certain parts of the Fermi surface. The data for T<~Tc can be well described by a strong-coupling extension of the BCS theory --- the \ensuremathα-model --- similar to what has been recently found for the \ensuremathκ\ensuremath-(BEDT\ensuremath-TTF)2Cu[N(CN)2]Br salt [Elsinger et al., Phys. Rev. Lett. 84, 6098 (2000)].