Electron states in quantum rings with defects under axial or in-plane magnetic fields

TL;DR

This paper investigates how geometric deformations and barriers in quantum rings affect electron states under magnetic fields, revealing that structural anisotropy significantly influences low-energy states and can be probed via in-plane magnetic responses.

Contribution

It provides a detailed analysis of the effects of anisotropic geometries and barriers on electron states in quantum rings under magnetic fields, combining numerical and analytical approaches.

Findings

Geometry deformations mainly affect low-lying states

Barriers have a strong, uniform impact on all states

In-plane magnetic response reveals structural anisotropy

Abstract

A comprehensive study of anisotropic quantum rings, QRs, subject to axial and in-plane magnetic field, both aligned and transverse to the anisotropy direction, is carried out. Elliptical QRs for a wide range of eccentricity values and also perfectly circular QRs including one or more barriers disturbing persistent QR current are considered. These models mimic anisotropic geometry deformations and mass diffusion occuring in the QR fabrication process. Symmetry considerations and simplified analytical models supply physical insight into the obtained numerical results. Our study demonstrates that, except for unusual extremely large eccentricities, QR geometry deformations only appreciably influence a few low-lying states, while the effect of barriers disturbing the QR persistent current is stronger and affects all studied states to a similar extent. We also show that the response of the electron states to in-plane magnetic fields provides accurate information on the structural anisotropy.