Spin-resolved electron waiting times in a quantum dot spin valve

TL;DR

This paper investigates spin-resolved electron waiting times in a quantum dot spin valve, revealing how spin correlations and transfer torque can be characterized through various waiting time distributions and their influence on spin dynamics.

Contribution

It introduces a detailed analysis of multiple types of waiting time distributions in a quantum dot spin valve, highlighting their relation to spin transfer torque and spin flip processes.

Findings

Cross-channel WTD characterizes spin transfer torque.

Influence degree quantifies spin flip processes.

Waiting time distributions reveal spin correlations.

Abstract

We study the electronic waiting time distributions (WTDs) in a non-interacting quantum dot spin valve by varying spin polarization and the noncollinear angle between the magnetizations of the leads using scattering matrix approach. Since the quantum dot spin valve involves two channels (spin up and down) in both the incoming and outgoing channels, we study three different kinds of WTDs, which are two-channel WTD, spin-resolved single-channel WTD and cross-channel WTD. We analyze the behaviors of WTDs in short times, correlated with the current behaviors for different spin polarizations and noncollinear angles. Cross-channel WTD reflects the correlation between two spin channels and can be used to characterize the spin transfer torque process. We study the influence of the earlier detection on the subsequent detection from the perspective of cross-channel WTD, and define the influence degree quantity as the cumulative absolute difference between cross-channel WTDs and first passage time distributions to quantitatively characterize the spin flip process. The influence degree shows a similar behavior with spin transfer torque and can be a new pathway to characterize spin correlation in spintronics system.