Thermoelectric voltage switching in gold atomic wire junctions

TL;DR

This study predicts that thermoelectric voltage in gold atomic wire junctions oscillates with the number of atoms and can change sign with mechanical stretching, offering potential for heat-to-electricity energy harvesting devices.

Contribution

It introduces a novel prediction of oscillating thermoelectric voltage in atomic wires, including sign changes due to stretching, supported by ab initio and semi-empirical calculations.

Findings

Thermoelectric voltage oscillates with atom number N.

Voltage amplitude scales with N for long chains.

Voltage sign can change upon stretching without changing N.

Abstract

We explore the thermoelectric properties of gold atomic chains bridging gold electrodes by means of \textit{ab initio} and semi-empirical calculations, and heuristic reasoning. We predict the thermoelectric voltage induced by a temperature difference across such junctions to oscillate, repeatedly changing sign, as a function of the number of atoms $N$ making up the atomic chain. We also predict the amplitude of the oscillations to be proportional to $N$ for long atomic chains. Further we predict the thermoelectric voltage to change sign, in some cases, if the junction is stretched without changing $N$. Our predictions apply regardless of whether regular or irregular electrode grain boundaries are present and whether the electrodes are symmetric or asymmetric. Our findings may pave the way to the realization of new mechanically controllable voltage switches enabling direct conversion of heat into electricity in energy harvesting applications.