Thermal Conductivity of Normal and Superconducting Aluminum

The thermal conductivity of three specimens of aluminum differing widely in residual resistivity was measured in the normal and superconducting states. The experimental method yielded quite accurate results of the ratio of the superconducting state thermal conductivity to that in the normal state, $\frac{{\kappa }_s}{{\kappa }_n}$. The ratios $\frac{{\kappa }_s}{{\kappa }_n}$, for specimens differing in electronic mean free path by as much as a factor of 140, were essentially the same over the range of temperature covered by the experiments, 0.32 to 1.20°K. Agreement of the experimental results with the theoretical predictions of Bardeen, Rickayzen, and Tewordt was quite good.