Ultrafast Radiative Heat Transfer

TL;DR

This paper predicts an ultrafast radiative cooling mechanism in graphene nanostructures, where over half of the electronic heat can be transferred between neighboring structures within femtoseconds, enabling new heat management strategies.

Contribution

It introduces a novel ultrafast radiative heat transfer regime in graphene nanostructures, highlighting the role of plasmonic fields and low heat capacity for efficient noncontact heat transfer.

Findings

>50% of heat transferred within femtoseconds

Ultrafast radiative cooling dominates in vacuum or isolated conditions

Potential application in heat management of nanostructures

Abstract

Light absorption in conducting materials produces heating of their conduction electrons, followed by relaxation into phonons within picoseconds, and subsequent diffusion into the surrounding media over longer timescales. This conventional picture of optical heating is supplemented by radiative cooling, which typically takes place at an even lower pace, only becoming relevant for structures held in vacuum or under extreme conditions of thermal isolation. Here we reveal an ultrafast radiative cooling regime between neighboring plasmon-supporting graphene nanostructures in which noncontact heat transfer becomes a dominant channel. We predict that >50% of the electronic heat energy deposited on a graphene disk can be transferred to a neighboring nanoisland within a femtosecond timescale. This phenomenon is facilitated by the combination of low electronic heat capacity and large plasmonic field concentration displayed by doped graphene. Similar effects should take place in other van der Waals materials, thus opening an unexplored avenue toward efficient heat management in ultrathin nanostructures.