Angular Conductance Resonances of Quantum Dots Non-Collinearly Coupled to Ferromagnetic Leads

TL;DR

This paper investigates how the conductance of quantum dots coupled to ferromagnetic leads varies with the angle between their magnetizations, revealing non-monotonic behavior due to spin-dependent effects in different coupling regimes.

Contribution

It demonstrates the angle-dependent conductance behavior in quantum dots with ferromagnetic leads, highlighting the impact of non-collinear magnetizations on quantum transport.

Findings

Conductance exhibits non-monotonic dependence on magnetization angle in strong coupling.

Spin split states and spin flip transitions influence conductance behavior.

System reverts to spin valve characteristics in weak coupling regime.

Abstract

The zero bias conductance of quantum dots coupled to ferromagnetic leads is investigated. In the strong coupling regime, it is found that the conductance is a non-monotonic function of the angle between the magnetisation directions in the two contacts. This behaviour is an effect of the presence of the leads which induces an angle dependent spin split of the quantum dot states, and spin flip transitions between the quantum dot states whenever the magnetisation directions of the leads are non-collinear which enhances the current density at the chemical potential. In the weak coupling regime, the system reverts to normal spin valve character.