Implications of cross-species interactions on the temperature dependence of Kapitza conductance

We investigate the behavior of Kapitza conductance at interfaces between two Lennard-Jones fcc solids as a function of the range and strength of cross-species interactions via molecular dynamics simulations. It is found that decreasing either of these quantities leads to a reduction in the slope of linear temperature dependence of Kapitza conductance, suggesting a corresponding decrease in the probability of inelastic phonon-phonon interactions. To further explore the mechanisms responsible for such behavior, we calculate the phonon density of states and spectral temperature of each of the monolayers adjacent to the interface. It is found that the reduction of the range and strength of cross-species interactions leads to a softening of the density of states near the interface, while the spectral temperature calculations provide further evidence that such reductions decrease the probability of inelastic phonon scattering. These findings help explain varying accounts of the temperature dependence of Kapitza conductance observed in previous works.