Investigation of in-plane nuclear field formation in single self-assembled quantum dots

TL;DR

This paper investigates the formation of in-plane nuclear fields in single self-assembled quantum dots, revealing anomalous Hanle curves and proposing a new model that incorporates nuclear quadrupole interactions and g-factor sign inversion.

Contribution

It introduces a novel model explaining in-plane nuclear field formation in quantum dots, accounting for observed anomalies in Hanle measurements.

Findings

Observation of anomalously wide and hysteretic Hanle curves

Successful reproduction of anomalies using the new model

Identification of nuclear quadrupole effects and g-factor sign inversion

Abstract

We studied the formation mechanism of the in-plane nuclear field in single self-assembled In$_{0.75}$Al$_{0.25}$As/Al$_{0.3}$Ga$_{0.7}$As quantum dots. The Hanle curves with an anomalously large width and hysteretic behavior at the critical transverse magnetic field were observed in many single quantum dots grown in the same QD sample. In order to explain the anomalies in the Hanle curve indicating the formation of a large nuclear field perpendicular to the photo-injected electron spin polarization, we propose a new model based on the current phenomenological model for dynamic nuclear spin polarization. The model includes the effects of the nuclear quadrupole interaction and the sign inversion between in-plane and out-of-plane g-factors, and the model calculations reproduce successfully the characteristics of the observed anomalies in the Hanle curves.