Thermal Conductivity and Electrical Resistivity of Terbium Between 5 and 300°K

Abstract

The thermal conductivity $\lambda$ of polycrystalline terbium has been studied as a function of temperature $T$ between 5 and 300°K. The $\lambda$-versus-$T$ curve exhibits a maximum of 0.205 W ${\mathrm{cm}}^{-1\mathrm{}}$ °${\mathrm{K}}^{-1\mathrm{}}$ at 23°K. The antiferromagnetic-paramagnetic transition, $T_{\mathrm{A}-\mathrm{P}}$, causes an anomaly in the thermal conductivity at about 225°K. The ferromagnetic-antiferromagnetic transformation, $T_{\mathrm{F}-\mathrm{A}}$, because of the narrow antiferromagnetic region, is not observable from the $\lambda$ versus-$T$ curve. According to the electrical resistivity data, $T_{\mathrm{F}-\mathrm{A}}=219\mathrm{}\pm 1°$K and $T_{\mathrm{A}-\mathrm{P}}=230\mathrm{}\pm 1°$K. The Lorenz function, calculated from the measured thermal conductivity and electrical resistivity values on the same sample, indicates that heat is transported mainly by electrons, with possible additional transport by phonons and magnons. The intrinsic electrical resistivity between 5 and 20°K is proportional to $T^{4.19\pm 0.06}$.