We report high-resolution specific-heat measurements on the quasi-two-dimensi-onal organic superconductorκ(BEDTTTF)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 ≪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 theorythe α-modelsimilar to what has been recently found for the κ-(BEDT-TTF)2Cu[N(CN)2]Br salt [Elsinger et al., Phys. Rev. Lett. 84, 6098 (2000)].
|Number of pages||4|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2002 Apr 1|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics