Thermal conductivity of quasi-two-dimensional organic superconductor k-(ET)2 Cu[N(CN)2]Br

The thermal k and electrical σ conductivities were measured on the same crystals of the quasi-2D organic superconductor k-(ET)2 Cu[N(CN)2]Br with Tc approx approx 11 K along the conducting ac-plane. It is shown that the heat transport is mainly controlled by the phonon component in the interval from room to helium temperatures. At temperatures above the k(T) maxima (T>15 K) the phonon mean free path λph was limited by the phonon-phonon and point defect scatterings. Below the k(T) maxima, the λph values were limited by scattering at macroscopic defects such as granular boundaries or dislocations in the bulk sample