Magnon transport and spin current switching through quantum dots

TL;DR

This paper investigates how quantum dots coupled to ferromagnetic insulators can control spin currents via magnon transport, revealing sensitive dependence on coupling configurations and identifying resonant phenomena.

Contribution

It introduces a detailed analysis of magnon-mediated spin transport through quantum dots, highlighting new mechanisms for spin switching and resonance effects.

Findings

Spin current is highly sensitive to coupling configurations.

Identification of 1- and 2-magnon transport resonances.

Distinct behavior compared to electronic transport.

Abstract

We study the nonequilibrium spin current through a quantum dot consisting of two localized spin-1/2 coupled to two ferromagnetic insulators. The influence of an intra-dot magnetic field and exchange coupling, different dot-reservoir coupling configurations, and the influence of magnon chemical potential differences vs. magnetic field gradients onto the spin current are examined. We discuss various spin switching mechanisms and find that, in contrast to electronic transport, the spin current is very sensitive to the specific coupling configuration and band edges. In particular, we identify 1- and 2-magnon transport processes which can lead to resonances and antiresonances for the spin current.