Temperature Dependence of Conductance and Thermopower Anomalies of Quantum Point Contacts

TL;DR

This paper investigates how temperature influences conductance and thermopower anomalies in quantum point contacts, revealing that electron interactions cause potential barrier pinning and lead to temperature-dependent conductance features.

Contribution

It introduces a simple model incorporating electron-electron interactions to explain temperature-dependent conductance and thermopower anomalies in quantum point contacts.

Findings

Conductance and thermopower anomalies are explained by potential barrier pinning at finite temperature.

The model's predictions match experimental observations of anomalous plateaux.

Electron-electron interactions significantly affect the temperature dependence of quantum contact properties.

Abstract

It has been shown within the Landauer single-channel approach that the presence of the 0.7 anomaly in the conductance of a ballistic microcontact and the respective plateau in the thermopower implies unusual pinning of the potential barrier height $U$ at a depth of $k_BT$ below the Fermi level $E_F$. A simple way of taking into account the effect of electron-electron interaction on the profile and temperature dependence of a smooth one-dimensional potential barrier in the lower spin degeneracy subband of the microcontact has been proposed. The calculated temperature dependences of the conductance and Seebeck coefficient agree with the experimental gate-voltage dependences, including the emergence of anomalous plateaux with an increase in temperature.