Thermal conductivity of LaB6: the role of phonons

The thermal conductivity of a high-conductivity metallic LaB6 single crysta l was measured in the temperature range between 0.7 and 30 K. The striking point of the observed temperature dependence is the non-linear behaviour of the thermal conductivity at lowest temperatures, where a linear dependence is expected. Additional measurements of electrical conductivity and in a m agnetic field show that the non-linearity originates from a scattering mech anism which leads to the decrease of the electronic component of the therma l conductivity. Scattering processes of conduction electrons by phonons and by magnetic impurities are discussed. (C) 1999 Elsevier Science B.V. All r ights reserved.