Anomalous Specific Heat of bccHe3

Abstract

The experimental specific-heat data for bcc ${\mathrm{He}}^3$ reported by Sample and Swenson (SS) have been reanalyzed to extract that portion expected theoretically to be due to phonon excitation. Use is made of the reduced Debye $\Theta$ versus temperature $T$ relationship calculated by de Wette, Nosanow, and Werthamer. This procedure establishes lower limits for the Debye temperatures ${\Theta }_0$ which are higher than those obtained by SS. The remaining, "anomalous," specific heat is fitted with a single exponential expression, ${\left(\frac{\varphi }{T}\right)}^2\exp (-\frac{\varphi }{T}){[1-\exp (-\frac{\varphi }{T}\left)\right]}^{-2\mathrm{}}$. The values of the characteristic temperatures $\varphi$ as a function of molar volume are fairly similar to those of SS. These procedures are not sufficiently accurate to decide between the various defect mechanisms that could give rise to the anomalous specific heat.