Kapitza conduction by thin lossy surface layers

The authors consider the Kapitza conductance due to absorption and emission of phonons by a lossy surface layer which has complex elastic constants and/or complex mass density. They find a series connection of two heat resistances, one between the layer and the solid, and another one between the layer and the helium. A propagator matrix formalism is used to calculate the phonon absorption coefficients, and hence the Kapitza conductance, as a function of angle, frequency and layer thickness in the limit of continuum acoustics with anisotropy. The resulting conductance is large enough to account for the Kapitza anomaly.