Description
Date/Time: 04-23-2019 - Tuesday - 05:00 PM - 07:00 PM
Ryan Duncan1 Samuel Huberman2 Ke Chen2 Bai Song2 Vazrik Chiloyan2 Zhiwei Ding2 Alexei Maznev1 Gang Chen2 Keith Nelson1

1, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
2, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States

Wavelike thermal transport in solids, referred to as second sound, has until now been an exotic phenomenon limited to a handful of materials at low temperatures. This has restricted interest in its occurrence and in its potential applications. Through time-resolved optical measurements of thermal transport on 5-20 μm length scales in graphite, we have made direct observations of second sound at temperatures above 100 K. The results are in qualitative agreement with ab initio calculations that predict wavelike phonon hydrodynamics on ~ 1-μm length scale up to almost room temperature. The results suggest an important role of second sound in microscale transient heat transport in two-dimensional and layered materials in a wide temperature range.

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