Lattice Thermal Conductivity and High-Field Electrical and Thermal Magnetoconductivities of Tungsten

Abstract

Measurements of the high-field transverse electrical and thermal conductivities ${\sigma }_{\mathrm{xx}}$ and ${\kappa }_{\mathrm{xx}}$ of a high-purity tungsten single crystal are presented for the temperature range 1.5-6 K. The magnetic field dependences of the conductivities conform excellently to the predictions of high-field semiclassical magnetoresistance theory, provided that thermal conduction by the lattice is taken into account. The results show that the lattice thermal conductivity is proportional to $T^2$, as expected for a pure metal in which the phonons are scattered principally by the conduction electrons. The temperature dependence of the high-field electrical conductivity ${\sigma }_{\mathrm{xx}}$, and the corresponding electronic contribution ${\left({\kappa }_e\right)}_{\mathrm{xx}}$ to the thermal conductivity ${\kappa }_{\mathrm{xx}}$ are also measured. Theoretical expressions for these quantities are derived from semiclassical magnetoresistance theory, allowing estimates to be made of the temperature dependence associated with possible low-temperature scattering mechanisms. Difficulties in interpreting previous zero-field measurements in terms of electron-electron or electron-phonon scattering are discussed.