Anomalous Lattice Specific Heat of Gold and Zinc at Liquid Helium Temperatures

Abstract

The heat capacities of both single-crystal and polycrystalline samples of gold and of zinc have been measured between 1.5 and 4.2°K. For gold the results may be represented accurately by an equation of the form $C=\gamma T+\beta T^3$, but the coefficient $\beta$ of the cubic term is significantly smaller than the value derived from low-temperature elastic constants measured on the same specimen. For zinc a polynominal expression of the results requires a $T^5$ term in addition to the usual linear and cubic terms. The $T^5$ term is positive, as in most other solids upon which measurements have been made, but is very large in magnitude, amounting to about one-fifth of the total heat capacity at 4°K. The agreement between the Debye temperatures near 0°K calculated from heat capacity and from low-temperature elastic constants measured on the same specimen may be within experimental error.