Thermal Magnetoconductivity of Tungsten Below 6 K: Combining the Zero-, Low- and High-Field Cases

We present a phenomenological expression to describe the thermal magnetoconductivity of tungsten which unifies the zero-field thermal conductivity with the low and high-field cases. Its basic form is derived from semi-classical magnetoresistance theory with fitting parameters allowing adjustment to particular samples. Thermal conductivity measurements at 5.5 K and in fields from 0 to 2 T are presented on two single crystals of tungsten with significantly different purities. We find that—with suitable adjustment of the fitting parameters—the equation is an excellent fit to the data in both cases. The significance of the fitting parameters and differences in their values are discussed, and we describe how they can be related to the individual properties of the samples. It is concluded that the equation should be applicable to any field below that at which orbit quantisation occurs and temperatures from 6 K down to tungsten’s superconducting transition.