Low-temperature properties of thin films

Abstract

It is shown that phonons in this films, "cut off" from a simple lattice, possess a gap whose magnitude depends upon the thickness of the film. Due to the presence of the gap, the specific heat of the film for T≈ 0 changes approximately as T-1 exp(-const/T). This behaviour of the specific heat can be used for experimental verification of the existence of the phonon gap. © 1992.