Engineered spin phase diagram of two interacting electrons in semiconductor nanowire quantum dots

TL;DR

This paper develops a theoretical framework to analyze the spin phase diagram of two interacting electrons in semiconductor nanowire quantum dots, revealing how geometry and magnetic fields influence spin states and transitions.

Contribution

It introduces an explicit 3D parabolic model and CI method for efficient analysis of Coulomb interactions and spin transitions in nanowire quantum dots.

Findings

Identification of spin singlet-triplet transitions influenced by geometry and magnetic fields.

Development of a versatile theoretical approach for different dimensional regimes.

Insights into the crossover from quasi-2D to 1D quantum dot behavior.

Abstract

Spin properties of two interacting electrons in a quantum dot (QD) embedded in a nanowire with controlled aspect ratio and longitudinal magnetic fields are investigated by using a configuration interaction (CI) method and exact diagonalization (ED) techniques. The developed CI theory based on a three-dimensional (3D) parabolic model provides explicit formulations of the Coulomb matrix elements and allows for straightforward and efficient numerical implementation. Our studies reveal fruitful features of spin singlet-triplet transitions of two electrons confined in a nanowire quantum dot (NWQD), as a consequence of the competing effects of geometry-controlled kinetic energy quantization, the various Coulomb interactions, and spin Zeeman energies. The developed theory is further employed to study the spin phase diagram of two quantum-confined electrons in the regime of "cross over" dimensionality, from quasi-two-dimensional (disk-like) QDs to finite one-dimensional (rod-like) QDs.