Phononic crystals have been studied for the past decades as a tool to control the propagation of acoustic and mechanical waves. Recently, researchers proposed that nanosized phononic crystals can also control heat conduction by phonon dispersion engineering using wave properties of phonons. In this project, we try to use phononic crystals to coherently control heat condution at nanoscale. We aim to experimentally test theoretical predictions of the thermal conductivity reduction caused by periodicity and local resonances.
Figure above summarizes our research on coherent thermal transport. Panel (a) shows thermal conductance “boost” effect when phononic crystal becomes more conductive than a membrane without holes due to phonon interference. Panel (b) shows tuning of thermal conductance via structure periodicity in various phononic crystals at low temperatures. Experiments on (c) hole-based phononic crystals of different lattices, (d) pillar-based phononic crystals, and (e) phononic crystals with ordered and disordered disordered lattices. At low temperatures, the difference between ordered and disordered lattices occurs, which indicates coherent regime.