Modulation of charge and spin circular currents in a ring-wire hybrid setup

TL;DR

This paper investigates how charge and spin circular currents in a mesoscopic hybrid system are influenced by AAH potential, AB flux, chemical potential, and AF order, revealing complex oscillatory behaviors and symmetry-breaking effects.

Contribution

It introduces a detailed model of a hybrid AF ring coupled to an AAH chain, analyzing the effects of various parameters on charge and spin currents, including symmetry-breaking mechanisms.

Findings

Charge current oscillates periodically with AB flux.

Spin current peaks due to interference from disorder-induced localization.

AAH potential shifts energy levels, affecting transport behavior.

Abstract

We present a comprehensive investigation into the charge and spin circular currents in a mesoscopic hybrid system, with a particular focus on the intricate interplay between the Aubry-Andr\'e-Harper (AAH) potential, Aharonov-Bohm (AB) flux, chemical potential ($\mu$), and antiferromagnetic (AF) ordering. The proposed quantum system comprises a composite structure of an AF ring coupled to an AAH chain. Utilizing a tight-binding model and operator method to calculate charge and spin circular currents, we uncover a range of intriguing phenomena. An interesting finding is that while the antiferromagnetic ring alone does not exhibit spin channel separation due to the symmetry between the up and down spin sub-Hamiltonians, the introduction of a dangling bond or chain can break this symmetry, leading to a spin separation effect. The AAH potential in the chain disrupts energy level symmetry, significantly impacting transport behavior. The charge circular current exhibits periodic oscillations with the AB flux, and its polarity changes with variations in $\mu$. The AAH phase affects the charge current through the shifting of energy levels. Furthermore, the spin current displays oscillatory behavior as the AAH potential strength changes, with peaks emerging due to interference phenomena caused by disorder-induced localization. A possible experimental realization of our proposed quantum setup is also discussed, for the sake of completeness. This work may provide important insights into the complex physics of charge and spin transport in various hybrid mesoscopic systems, offering promising avenues for future research and technological applications.