Tunnel magnetoresistance of quantum dots coupled to ferromagnetic leads in the sequential and cotunneling regimes

TL;DR

This paper investigates how quantum dots coupled to ferromagnetic leads exhibit tunnel magnetoresistance (TMR) across various regimes, considering both sequential and cotunneling processes, and analyzing effects of resonance and electron number parity.

Contribution

It provides a comprehensive analysis of TMR in quantum dots, including first and second order tunneling effects, across multiple transport regimes and electron configurations.

Findings

Different TMR behaviors arise from various transport mechanisms.

Spin accumulation significantly influences TMR in different regimes.

TMR varies with resonance conditions and electron parity.

Abstract

We study electronic transport through quantum dots weakly coupled to ferromagnetic leads with collinear magnetization directions. Tunneling contributions of first and second order in the tunnel-coupling strength are taken into account. We analyze the tunnel magnetoresistance (TMR) for all combinations of linear and nonlinear response, at or off resonance, with an even or odd dot-electron number. Different mechanisms for transport and spin accumulation the various regimes give rise to different TMR behavior.