Electron and phonon drag in thermoelectric transport through coherent molecular conductors

TL;DR

This paper investigates the mutual drag effect between electrons and phonons in coherent molecular conductors, revealing its connection to charge pumping and magnetic forces, using nonequilibrium Green's function methods.

Contribution

It derives linear drag coefficients obeying Onsager relations and explores their impact on thermoelectric transport in molecular conductors.

Findings

Drag effect is linked to adiabatic charge pumping.

Electron-phonon mutual drag influences nonequilibrium transport.

Drag coefficients satisfy Onsager reciprocity.

Abstract

We study thermoelectric transport through a coherent molecular conductor connected to two electron and two phonon baths using the nonequilibrium Green's function method. We focus on the mutual drag between electron and phonon transport as a result of `momentum' transfer, which happens only when there are at least two phonon degrees of freedom. After deriving expressions for the linear drag coefficients, obeying the Onsager relation, we further investigate their effect on nonequilibrium transport. We show that the drag effect is closely related to two other phenomena: (1) adiabatic charge pumping through a coherent conductor; (2) the current-induced nonconservative and effective magnetic forces on phonons.