Spin-dependent thermoelectric transport coefficients in near-perfect quantum wires

TL;DR

This paper investigates spin-dependent thermoelectric properties in near-perfect quantum wires, revealing robust anomalies in conductance and thermopower due to electron resonances, and discusses deviations from classical laws at higher temperatures.

Contribution

It extends previous conductance studies to include thermopower and thermal conductance, demonstrating their anomalous behavior and temperature robustness within the Landauer-Büttiker framework.

Findings

Anomalous structures in thermopower and thermal conductance are observed.

Thermal conductance deviates from Wiedemann-Franz law at elevated temperatures.

Anomalies persist up to a few degrees Kelvin.

Abstract

Thermoelectric transport coefficients are determined for semiconductor quantum wires with weak thickness fluctuations. Such systems exhibit anomalies in conductance near 1/4 and 3/4 of 2e^2/h on the rising edge to the first conductance plateau, explained by singlet and triplet resonances of conducting electrons with a single weakly bound electron in the wire [T. Rejec, A. Ramsak, and J.H. Jefferson, Phys. Rev. B 62, 12985 (2000)]. We extend this work to study the Seebeck thermopower coefficient and linear thermal conductance within the framework of the Landauer-Buettiker formalism, which also exhibit anomalous structures. These features are generic and robust, surviving to temperatures of a few degrees. It is shown quantitatively how at elevated temperatures thermal conductance progressively deviates from the Wiedemann-Franz law.