Thermal conductivity of niobium diselenide

Thermal conductivity measurements have been used to study the temperature dependence of the various scattering mechanisms present in single crystals of NbSe in a temperature range from 1 to 10/sup 0/K. Phonons are found to contribute a substantial fraction of the conduction in this temperature range and, in general, the results agree well with standard theoretical models for three-dimensional metals. The presence of van der Waals boundaries beween the layers introduces no significant boundary scattering for phonons. In addition to the usual electron and point defect scattering terms which are present in the phonon conductivity, a term which has a linear temperature dependence was found. This linear term may be caused by stacking fault scattering centers. A linear field dependence of the electrical magnetoresistance is reported and it is suggested this term may arise from magnetic breakdown at energy gaps in the Fermi surface induced by charge-density waves as suggested by Overhauser. It is noted that the ratio of the superconducting to normal state thermal conductivity is consistent with a BCS-like superconducting energy gap.