About the hump in the low-temperature isochoric heat capacity of Ne cryocrystals

The low-temperature dependence of the heat capacity of Ne cryocrystals was analyzed. A hump that appears as a local maximum in the heat capacity curve is shown as C/T3 vs T at Tmax. It was observed that with increasing molar volume, the Tmax shifts to lower temperatures. A universal empirical relation Δ∗ was proposed to describe the excess (non-Debye) heat capacity at low temperatures. It was shown that the value of the universal function Δ∗ depends on both the magnitude of the heat capacity anomaly and the temperature at which the hump occurs, but remains universal and independent of molar volume for noble gas cryocrystals. This study provides new information about the potential origins of the hump in the heat capacity as a manifestation of the first van Hove singularity. The study’s results may be useful in addressing the issue of the calorimetric boson peak in amorphous and disordered solids.