Enhancement of the phonon heat capacity in metals at low temperature
Abstract
Landau damping of each phonon mode causes its spectral density to acquire a low-frequency tail proportional to ω2. Consequently the T3 low-temperature heat capacity arising from acoustic modes, with a frequency spectrum proportional to ν2, is supplemented by the spectral-density tails from all modes in the Brillouin zone. This extra term is proportional to T3ln(ΘT) and is a few percent of the Debye term at 1 K. In metals with large electron-phonon interaction-e.g., superconductors-the extra term will be larger, and will be present only in the normal state. A lower T3 coefficient should occur in the superconducting state, a phenomenon reported experimentally for indium 20 years ago, since the spectral-density tail falls to zero for frequencies below the energy gap.
- Publication:
-
Physical Review B
- Pub Date:
- August 1982
- DOI:
- 10.1103/PhysRevB.26.1569
- Bibcode:
- 1982PhRvB..26.1569D