Near-field radiative heat transfer modulated by nontrivial topological surface states

Abstract

Three-dimensional topological insulators (3D TIs), such as Bi2Se3 and Bi2Te3, possessing insulating bulk states and nontrivial topological surface states protected by time-reversal symmetry, have attracted considerable attention. In this paper, we investigate the near-field radiative heat transfer in 3D TIs, which can be strongly modulated by the non-trivial surface states. Full 3D TI properties including both the bulk and surface states are considered in our theoretical study. We show that the hybrid polaritons in single-material TI films, resulting from the coupling of Dirac plasmons on the top and bottom surfaces with the multiple phonon polariton modes supported by the bulk states including hyperbolic phonon polaritons (HPP), surface phonon polaritons (SPhP) and epsilon-near-pole (ENP) modes, can strongly mediate and enhance the near-field thermal radiation. The dispersions of hybrid polaritons intensely depend on the chemical potential of the surface and the film thickness, and by tuning both separately, we can control the coupling and competition between the surface and bulk modes, and thus modulate the radiative spectrum and heat flux. In addition, the nonlocal optical response of the surface states has a remarkable impact on the mode hybridization. This work demonstrates the potential of 3D TIs in manipulating near-field thermal radiation, which may provide a useful platform for energy conversion and thermal management.