Non-collinear magnetoconductance of a quantum dot

TL;DR

This paper investigates how non-collinear magnetic fields and Coulomb interactions affect the conductance of a quantum dot connected to ferromagnetic leads, revealing anti-resonances and interaction-induced conductance enhancements.

Contribution

It provides an exact solution for non-interacting cases and explores Coulomb correlation effects, highlighting differences in conductance behavior based on lead magnetization alignment.

Findings

Anti-resonance occurs at specific non-collinear field directions in non-interacting case.

Coulomb interactions destroy the anti-resonance, enhancing conductance.

Interactions have minimal effect on angle dependence for anti-parallel lead magnetizations.

Abstract

We study theoretically the linear conductance of a quantum dot connected to ferromagnetic leads. The dot level is split due to a non-collinear magnetic field or intrinsic magnetization. The system is studied in the non-interacting approximation, where an exact solution is given, and, furthermore, with Coulomb correlations in the weak tunneling limit. For the non-interacting case, we find an anti-resonance for a particular direction of the applied field, non-collinear to the parallel magnetization directions of the leads. The anti-resonance is destroyed by the correlations, giving rise to an interaction induced enhancement of the conductance. The angular dependence of the conductance is thus distinctly different for the interacting and non-interacting cases when the magnetizations of the leads are parallel. However, for anti-parallel lead magnetizations the interactions do not alter the angle dependence significantly.