Spin Related Effects in Transport Properties of "Open" Quantum Dots

TL;DR

This paper investigates how electron-electron interactions influence electrical and thermal transport in open quantum dots, revealing significant effects of triplet interactions, magnetic fields, and violations of classical laws like Wiedemann-Franz.

Contribution

It provides a comprehensive analysis of interaction effects on transport properties in open quantum dots using a quantum kinetic approach, including the impact of magnetic fields and contact reflection.

Findings

Triplet channel interactions significantly affect differential conductance.

Magnetic fields cause Zeeman splitting, altering conductance and creating finite bias anomalies.

Interaction corrections violate the Wiedemann-Franz law in thermal conductance.

Abstract

We study the interaction corrections to the transport coefficients in open quantum dots (i.e. dots connected to leads of large conductance $G \gg e^2/\pi\hbar$), via a quantum kinetic equation approach. The effects of all the channels of the universal (in the Random Matrix Theory sense) interaction Hamiltonian are accounted for at one loop approximation. For the electrical conductance we find that even though the magnitude of the triplet channel interaction is smaller than the charging energy, the differential conductance at small bias is greatly affected by this interaction. Furthermore, the application of a magnetic field can significantly change the conductance due to the Zeeman splitting, producing finite bias anomalies. For the thermal conductance we find that the Wiedemann-Franz law is violated by the interaction corrections, and we investigated the effect of magnetic field on the Lorentz ratio for contacts of finite reflection. The charge and triplet channel corrections to the electrical and thermal conductance vanish for reflectionless contacts. In the latter case the temperature and magnetic field dependence of the conductance is determined by the Maki-Thompson correction in the Cooper channel.