Phonon filtering for reduced thermal conductance in unconventional superlattices

The thermal transport of an unconventional superlattice is investigated by nonequilibrium molecular dynamics simulation. It is shown that the thermal conductance of a two-order superlattice decreases by 15–29% as compared with that of a conventional superlattice. This result is unambiguously explained by the phonon transmission functions of similar one-dimensional superlattice atomic chains calculated by Green's function method. It is demonstrated that the multiscale structure introduces additional phonon bandgaps, leading to the reduction in thermal conductance due to phonon filtering effects. The proposed unconventional superlattice may find potential applications in phonon engineering, such as thermoelectrics and thermal isolation.