Current Rectification and Seebeck Coefficient of Serially Coupled Double Quantum Dots

TL;DR

This paper theoretically investigates the transport properties of serially coupled quantum dots, focusing on current rectification, negative differential conductance, spin-polarization, and Seebeck coefficient behavior under various conditions.

Contribution

It provides new insights into the rectification and thermoelectric properties of SCQDs, including spin effects and electron-phonon interactions, under both linear and nonlinear regimes.

Findings

Current rectification and negative differential conductance are due to bias-dependent probabilities and off-resonant levels.

Spin-polarization current rectification occurs under the Zeeman effect, with maximum in forward bias.

Seebeck coefficient exhibits nonlinear behavior, suggesting potential for temperature detection.

Abstract

The transport properties of serially coupled quantum dots (SCQDs) embedded in a matrix connected to metallic electrodes are theoretically studied in the linear and nonlinear regimes. The current rectification and negative differential conductance of SCQDs under the Pauli spin blockade condition are attributed to the combination of bias-direction dependent probability weight and off-resonant energy levels yielded by the applied bias across the junctions. We observe the spin-polarization current rectification under the Zeeman effect. The maximum spin-polarization current occurs in the forward bias regime. Such behavior is different from the charge current rectification. Finally, the Seebeck coefficient ($S$)of SCQDs is calculated and analyzed in the cases without and with electron phonon interactions. The application of SCQDs as a temperature detector is discussed on the basis of the nonlinear behavior of $S$ with respect to temperature difference across the junction.