Hydrodynamic signatures in thermal transport in devices based on 2D materials: an ab initio study

TL;DR

This study uses ab initio calculations and Monte Carlo methods to analyze hydrodynamic effects in thermal transport within 2D material devices, revealing boundary scattering and sample size as key factors.

Contribution

It provides a detailed ab initio analysis of hydrodynamic thermal transport in 2D materials, emphasizing the role of boundary effects and nonlocal length in hydrodynamic signatures.

Findings

Boundary scattering influences hydrodynamic features

Sample dimensions relative to nonlocal length are critical

Approximations in scattering operators affect hydrodynamic signatures

Abstract

We investigate the features arising from hydrodynamic effects in graphene and phosphorene devices with finite heat sources, using ab initio calculations to go beyond Callaway's model and inform a full linearized scattering operator, and solving the phonon Boltzmann transport equation through energy-based deviational Monte Carlo methods. We explain the mechanisms that create those hydrodynamic features, showing that boundary scattering and the relation of sample dimensions to the nonlocal length are the determinant factors, regardless of the relative importance of normal versus resistive scattering. From this point of view, the nonlocal length reflects the ability of scattering to randomize the heat flux, and we show that approximations made on the scattering operator may have, through the value of nonlocal length, qualitative consequences on the signatures of hydrodynamic behavior.