Transport through quantum-dot spin valves containing magnetic impurities

TL;DR

This paper explores how magnetic impurities affect electron transport in quantum-dot spin valves, revealing complex spin dynamics, noise characteristics, and potential for studying spin behavior via Fano factors.

Contribution

It introduces a detailed analysis of transport phenomena in quantum-dot spin valves with magnetic impurities, highlighting the role of exchange interactions and spin-dependent effects.

Findings

Current-induced spin switching and spin accumulation effects.

Large Fano factors indicating telegraph noise.

Distinct transport signatures depending on impurity position.

Abstract

We investigate transport through a single-level quantum dot coupled to noncollinearly magnetized ferromagnets in the presence of localized spins in either the tunnel barrier or on the quantum dot. For a spin embedded in the tunnel barrier, we find an interplay between current-induced switching of the spin, spin-dependent tunneling through the barrier and spin accumulation on the dot resulting in characteristic signals in the current. We, furthermore, find huge Fano factors due to random telegraph noise. For noncollinear geometries, an exchange field that depends on the impurity spin state leads to characteristic fingerprints in the transport properties. In the case of a spin on the quantum dot, we find that the frequency-dependent Fano factor can be used to study the nontrivial dynamics of the spins on the dot due to the interplay between exchange interaction and coupling to external and exchange magnetic fields.