Electronic pumping of heat without charge transfer

TL;DR

This paper proposes a novel electron-mediated heat pumping mechanism in charge-neutral systems like graphene, which operates without net charge transfer and offers potential advantages over traditional thermoelectric methods.

Contribution

It introduces a new heat pumping mechanism in charge-neutral electron systems and analyzes its efficiency and flux in different regimes, including the hydrodynamic limit.

Findings

Heat flux remains finite even for infinitesimal potentials in pristine systems.

Perfect pumping occurs with a traveling wave potential moving at velocity c.

Heat flux depends on cycle geometry and disorder strength.

Abstract

A mechanism of electron-mediated pumping of heat in the absence of net charge transfer is proposed. It may be realized in charge-neutral electron systems, such as graphene, coupled to an external electric potential. The flow of heat in this pumping cycle is not accompanied by a buildup of voltage along the system, which offers advantages over traditional thermoelectric cooling setups. Efficiency of heat pumping and magnitude of heat flux are studied in the hydrodynamic regime for weak disorder. In a pristine system, even for an infinitesimal pumping potential the heat flux remains finite. In particular, for a potential in the form of a traveling wave moving with velocity $c$ the pumping is perfect; the entire heat content of the electron liquid is advected with velocity $c$. For a general pumping cycle the heat flux is determined by the cycle geometry and disorder strength.