Interaction-driven spin precession in quantum-dot spin valves

TL;DR

This paper investigates how electron interactions and spin precession in a quantum dot influence spin-dependent transport in spin valves, revealing a reduced spin-valve effect due to bias-induced spin torque.

Contribution

It provides a theoretical analysis of spin precession effects in quantum-dot spin valves considering electron interactions and bias voltage, deriving conductance dependence on lead magnetization angles.

Findings

Spin accumulates on the quantum dot under bias.

Spin precession causes a non-trivial angle dependence of conductance.

Spin-valve effect is diminished for all angles except antiparallel.

Abstract

We analyze spin-dependent transport through spin valves composed of an interacting quantum dot coupled to two ferromagnetic leads. The spin on the quantum dot and the linear conductance as a function of the relative angle $\theta$ of the leads' magnetization directions is derived to lowest order in the dot-lead coupling strength. Due to the applied bias voltage spin accumulates on the quantum dot, which for finite charging energy experiences a torque, resulting in spin precession. The latter leads to a non-trivial, interaction-dependent, $\theta$-dependence of the conductance. In particular, we find that the spin-valve effect is reduced for all $\theta \neq \pi$.