Heat conduction engineering in pillar-based phononic crystals


Pillar-based phononic crystals belong to a class of acoustic metamaterials that can control heat conduction based on the design of the structure. In this work, we systematically investigate how various parameters of pillar-based phononic crystals affect thermal conductance at low temperatures. We find that the lowest thermal conductance is achieved when the pillars are short, have a large radius, a long period, and are made of materials with few local resonances, whereas pillars with many local resonances can, on the contrary, increase thermal conductance. We argue that properly designed pillar-based phononic crystals can serve as an alternative to conventional hole-based phononic crystals because local resonances in pillars introduce additional degrees of freedom, which allows not only suppressing but also enhancing heat conduction. Moreover, we propose hybrid hole/pillar-based phononic crystals that can further reduce thermal conductance.

Physical Review B 95, 155432 (2017)