THERMAL-CONDUCTIVITY OF ORGANIC SUPERCONDUCTORS

We have studied the thermal conductivity kappa(T) and resistivity rho( T) of quasi-two-dimensional organic superconductor kappa-(ET)(2)Cu[N(C N)(2)]Br (with T-c approximate to 11 K) from room to liquid helium tem peratures. Estimations of the electron contribution kappa(e) by Wiedem an-Franz law in the total conductivity k(T) have shown the predominanc e of the lattice component (kappa(p) similar to 10(3) kappa(e)). The b ehavior of thermal conductivity at high temperature (100-300 K) descri bed the amorphous-like temperature dependence. The sharp bends on kapp a(T) and rho(T) at T near 70 K correlate with the known disorder-order phase transition. An increase of the thermal conductivity k(T) simila r to T-1 below 70 K can be ascribed to the phonon-phonon interaction i n bulk of the samples (the Debye phonon model), though at high tempera tures the experimental results are better fitted by Einstein model.