Going beyond Landauer scattering theory to describe spatially-resolved non-local heating and cooling in quantum thermoelectrics

TL;DR

This paper develops a combined Landauer-Boltzmann model to accurately describe non-local heat transfer in quantum thermoelectric nanostructures, revealing effects overlooked by traditional Landauer scattering theory.

Contribution

It introduces a hybrid theoretical framework that captures non-local heating and cooling effects in nanostructures, extending beyond standard Landauer scattering theory.

Findings

Non-local Joule heating and Peltier cooling are revealed.

Heating and cooling effects can be opposite to Landauer predictions.

Phonon hot and cold spots are spatially separated from scatterers.

Abstract

Spatially-resolved heating and cooling in nanostructures is nowadays measured with various nanoscale thermometry techniques, including scanning thermometry. Yet the most commonly used theory of nanoscale heating and thermoelectricity -- Landauer scattering theory -- is not appropriate to model such measurements. Hence, we analyze a minimal model of spatially-resolved heat transfer between electrons and phonons in simple thermoelectric nanostructures. This combines Landauer scattering formalism with a Boltzmann equation for transport, revealing the non-locality of Joule heating and Peltier cooling induced by a scatterer in a nanowire. The corresponding heating or cooling of the phonons is caused by the voltage drop at the scatterer, but is often maximal at a certain distance from the scatterer. This distance is of the order of the electron-phonon scattering length. Scanning thermal microscopy, such as SQUID-on-tip thermometers, should detect this non-locality as phonon hot spots and cold spots, spatially separated from the scatterer. We provide physical arguments explaining the thermoelectric response of the combined system of wire and scatterer, and in particular, why the resulting heating and cooling is sometimes the opposite to that predicted by the standard Landauer scattering theory.