When quantum materials get hot: anomalous thermal conduction and radiation

Heat conduction in and radiation from solids provides a unique window to probe solid state physics, and also plays a pivotal role for a wide range of industry applications. Although it is a traditional research focus in mechanical engineering, study of heat transfer from materials scientists’ perspective would result in new discovery, new insight and new applications. 

In this talk, I will show our recent work on understanding novel charge dynamics and electron-phonon interactions of quantum materials with electronic phase transitions. An unusually low electronic thermal conductivity is found in metallic vanadium dioxide, and is a signature of absence of quasiparticles in a strongly correlated electron fluid where heat and charge diffuse independently. An unusual, temperature-independent lattice thermal conductivity is found in crystalline tantalum disulfide, which is attributed to strong electron-phonon coupling that dominates over the conventional phonon-phonon scattering. 

I will also discuss how we engineer these materials for novel thermal applications. By grading or meta-structuring the metal-insulator phase transition, we demonstrate temperature-indepdendent thermal radiation which is used for a superior infrared camouflage and decoy, as well as switchable thermal radiation which is used for thermal imaging gradient enhancing.

Speaker: Junqiao Wu, UC Berkeley