Super-Planckian electron cooling in a van der Waals stack

TL;DR

This paper develops a microscopic theory showing that radiative heat transfer between graphene and hBN in van der Waals stacks is highly efficient, enabling ultrafast carrier cooling at room temperature due to hyperbolic phonon-polaritons.

Contribution

It introduces a microscopic model of radiative heat transfer in van der Waals heterostructures involving graphene and hBN, highlighting ultrafast cooling mechanisms.

Findings

RHT between graphene and hBN is extremely efficient at room temperature.

Carrier cooling occurs on picosecond timescales.

Hyperbolic phonon-polaritons facilitate enhanced heat transfer.

Abstract

Radiative heat transfer (RHT) between macroscopic bodies at separations that are much smaller than the thermal wavelength is ruled by evanescent electromagnetic modes and can be orders of magnitude more efficient than its far-field counterpart, which is described by the Stefan-Boltzmann law. In this Letter we present a microscopic theory of RHT in van der Waals stacks comprising graphene and a natural hyperbolic material, i.e. hexagonal boron nitride (hBN). We demonstrate that RHT between hot carriers in graphene and hyperbolic phonon-polaritons in hBN is extremely efficient at room temperature, leading to picosecond time scales for the carrier cooling dynamics.