The effect of coherent optical phonon on thermal transport

Phonons are quantized lattice vibrations and the major heat carriers in most crystalline materials. We have been utilizing femtosecond phonon spectroscopy to excite and detect optical coherent phonons (CPs) in various materials. However, the impact of CPs to overall thermal transport is still unknown. In this study, we developed a small perturbation model in MD to simulate CPs and investigate the effects of CPs on thermal transport in Bi2Te3 at temperatures ranging from 20 to 325 K. The phonon frequency and lifetime predicted by our model agree very well with experimental results. It is found that the effective thermal transport estimated with the heat current autocorrelation function shows a great enhancement upon CP generation and extension, especially at low temperatures. Our results suggest that it is possible to manipulate thermal transport effectively with CPs.