Role of asymmetry in thermoelectric properties of a double quantum dot out of equilibrium

TL;DR

This paper explores how asymmetry in coupling and energy levels in a double quantum dot system affects thermoelectric properties like the Seebeck coefficient and current rectification, providing analytical insights.

Contribution

It reveals that moderate coupling asymmetry enhances thermoelectric efficiency and demonstrates conditions for effective current rectification based on energy level asymmetry.

Findings

Moderate asymmetry boosts the Seebeck coefficient.

Rectification occurs when energy levels are non-degenerate.

Analytical results explain rectification dependence on system parameters.

Abstract

We investigate the thermoelectric properties of a double quantum dot system coupled to two metallic reservoirs, focusing on two main effects: (i) the influence of coupling asymmetry between the quantum dot and the reservoirs on the Seebeck coefficient, and (ii) the impact of asymmetry in the energy levels of the dots on current rectification. In the first case, we find that introducing moderate asymmetry significantly enhances the Seebeck coefficient. In the second case, while rectification vanishes when the energy levels are degenerate, substantial rectification is achieved when one energy level lies below and the other above the Fermi level. We further interpret the dependence of rectification magnitude and shape on system parameters using analytical results from a spinless model.