Abstract
Recent studies of thermal transport in nanomaterials have demonstrated the breakdown of Fourier's law through observations of ballistic transport. Despite its unique features, another instance of the breakdown of Fourier's law, hydrodynamic phonon transport, has drawn less attention because it has been observed only at extremely low temperatures and narrow temperature ranges in bulk materials. Here, we predict on the basis of first-principles calculations that the hydrodynamic phonon transport can occur in suspended graphene at significantly higher temperatures and wider temperature ranges than in bulk materials. The hydrodynamic transport is demonstrated through drift motion of phonons, phonon Poiseuille flow and second sound. The significant hydrodynamic phonon transport in graphene is associated with graphene's two-dimensional features. This work opens a new avenue for understanding and manipulating heat flow in two-dimensional materials.
Highlights
Recent studies of thermal transport in nanomaterials have demonstrated the breakdown of Fourier’s law through observations of ballistic transport
The drift motion of phonons in the hydrodynamic regime causes two interesting hydrodynamic transport phenomena that cannot occur in either diffusive or ballistic regimes: phonon Poiseuille flow (Fig. 1a) and second sound (Fig. 1c), which are analogous to Poiseuille flow and Diffusive ordinary sound in a fluid, respectively, which will be discussed later
Using first-principles calculations, we show drift motion of phonons, phonon Poiseuille flow and second sound in graphene at significantly higher and wider temperature ranges compared with those seen in threedimensional materials
Summary
Recent studies of thermal transport in nanomaterials have demonstrated the breakdown of Fourier’s law through observations of ballistic transport. Another instance of the breakdown of Fourier’s law, hydrodynamic phonon transport, has drawn less attention because it has been observed only at extremely low temperatures and narrow temperature ranges in bulk materials. Regimes where Fourier’s law breaks down, such as ballistic[1] and hydrodynamic[2] phonon transport, were discovered in bulk materials more than 50 years ago, but these phenomena were observed only at extremely low temperatures[3,4,5]. Despite the interesting features of hydrodynamic phonon transport, the temperature range in which it was observed was too low and narrow to consider for practical applications. Using first-principles calculations, we show drift motion of phonons, phonon Poiseuille flow and second sound in graphene at significantly higher and wider temperature ranges compared with those seen in threedimensional materials. We discuss how the significant hydrodynamic phonon transport in graphene stems from its two-dimensional features
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