Specific Heats of Metals Below One Degree Absolute

Abstract

The heat capacities of a number of metals have been measured in the region below 1\ifmmode^\circ\else\textdegree\fi{}K, using the technique of adiabatic demagnetization. Copper, silver, platinum, palladium, tungsten, molybdenum, and sodium have been investigated. Apart from sodium, all exhibit a linear dependence of electronic specific heat on temperature. The values of $\ensuremath{\gamma}$ are in agreement with those obtained in the liquid helium region, except in the case of tungsten, which gives $\ensuremath{\gamma}=3.5\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ cal/mole ${\mathrm{deg}}^{2}$ in contrast to the previous value $\ensuremath{\gamma}=1.8\ifmmode\pm\else\textpm\fi{}0.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ cal/mole ${\mathrm{deg}}^{2}$ reported in the literature. Sodium exhibits an anomalous peak in its specific heat curve. A low-temperature, martensitic-type transformation is advanced as a likely cause of this behavior.In the course of the experiments, an independent measurement of the heat capacity of copper potassium sulfate has been made. The relation $C=\frac{A}{{T}^{2}}$ appears to be obeyed, the value of the specific heat constant $A$ being $5.8\ifmmode\pm\else\textpm\fi{}0.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}R$ ${\mathrm{deg}}^{2}$/mole.