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

Measurements of the high-field transverse electrical and thermal conductivities σₓₓ and κₓₓ 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 T², 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 σₓₓ, and the corresponding electronic contribution (κₑ)ₓₓ to the thermal conductivity κₓₓ 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.