Mechanisms causing thermal rectification: The influence of phonon frequency, asymmetry, and nonlinear interactions

Abstract

We have determined the mechanisms leading to thermal rectification by applying the nonequilibrium Green's function method to study thermal transport through a one-dimensional asymmetric lattice. Thermal rectification occurs in the presence of nonlinear interactions and a nonuniform phonon frequency distribution. We show that thermal rectification results from the contribution of high-frequency phonons; a thermal rectifier can thus be realized by filtering out high-frequency phonons in a single direction. Using these results, we present methods of increasing the level of rectification, and also discuss possible limitations on thermal rectifier performance. © 2008 The American Physical Society.