Specific Heat of Copper, Silver, and Gold below 30°K

The specific heats of pure copper, silver, and gold have been measured in an automatic calorimeter in the range 2.5-30°K. Above 20°K the results on copper and gold differ by up to 1% from the author's previous results on these metals—most probably owing to an unstable germanium thermometer used in the earlier work. The new results are analyzed together with data in the 0.4-3.0°K range and give the following values for electronic-specific-heat coefficient ($\gamma$), electron effective mass ($\frac{m^{*}}{m}$), and low-temperature limiting Debye temperature (${\Theta }_0^c$). The error limits are 95% confidence limits from the statistical analysis and do not include possible systematic errors. Copper: $\gamma =165.0\mathrm{}\pm 0.2$ μcal/°${\mathrm{K}}^2$ g atom (0.691 ± 0.001 mJ/°${\mathrm{K}}^2$ g atom); $\frac{m^{*}}{m}=1.38\mathrm{}$, ${\Theta }_0^c=(344.3\mathrm{}\pm 0.2)$°K. Silver: $\gamma =152.8\mathrm{}\pm 0.2$ μcal/°${\mathrm{K}}^2$ g atom (0.640 ± 0.001 mJ/°${\mathrm{K}}^2$ g atom); $\frac{m^{*}}{m}=1.00\mathrm{}$; ${\Theta }_0^c=(226.6\mathrm{}\pm 0.2)$°K. Gold: $\gamma =164.7\mathrm{}\pm 0.3$ μcal/°${\mathrm{K}}^2$ g atom (0.689 ± 0.001 mJ/°${\mathrm{K}}^2$ g atom); $\frac{m^{*}}{m}=1.08\mathrm{}$; ${\Theta }_0^c=(161.8\mathrm{}\pm 0.2)$°K. The results are briefly compared with other recent work on these metals.