Thermal conductivity of normal liquidHe3

The thermal conductivity $\kappa$ of normal liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ was measured along isochores for $7 \mathrm{mK} <T\lesssim 1 \mathrm{K}$ and for $0<P<\mathrm{}30\mathrm{}$ bars. The data, obtained using the standard steady-state heat-flow method, are based on the same temperature scale recently used for specific-heat measurements. They are ∼10% smaller than earlier low-temperature results obtained near $P=0\mathrm{}$. Extrapolations of the data to $T=0\mathrm{}$ are in very good agreement with the $s$- and $p$- wave approximation if the most-recently-determined quasiparticle effective mass is used. At very-low temperatures the data are consistent with theory which predicts that at low-but-finite temperature $\frac{1}{\kappa T}$ should have the form $a+bT$. However, contrary to the earlier measurements at $P=0\mathrm{}$, the new results clearly indicate that higher-order terms are also significant. With the combination of thermal-conductivity and specific-heat results, values of the scattering time ${\tau }_{\kappa }$ were determined. By fitting $\frac{1}{{\tau }_{\kappa }{T}^2}$ to an expression of the form $a_{\tau }+b_{\tau }T+c_{\tau }{T}^2\ln \left(\frac{T}{{\Theta }_{\tau }}\right)$ we found values of the characteristic temperature ${\Theta }_{\tau }$ which agree well with those extracted from the $T^3\ln T$ correction to the low-temperature specific heat.