Singlet-triplet avoided crossings and effective $g$ factor versus spatial orientation of spin-orbit-coupled quantum dots

TL;DR

This paper investigates how the orientation of anisotropic quantum dots affects spin-orbit-induced avoided crossings and the effective g factor, revealing significant modulation depending on crystal plane orientation.

Contribution

It demonstrates the dependence of avoided crossing widths and g factor on quantum dot orientation within the (001) plane, highlighting the role of Rashba and Dresselhaus interactions.

Findings

Avoided crossing width varies by two orders of magnitude with orientation.

Effective g factor depends on the quantum dot's orientation.

Spin polarization effects modulate spin-orbit coupling effects.

Abstract

We study avoided crossings opened by spin-orbit interaction in the energy spectra of one- and two-electron anisotropic quantum dots in perpendicular magnetic field. We find that for simultaneously present Rashba and Dresselhaus interactions the width of avoided crossings and the effective $g$ factor depend on the dot orientation within (001) crystal plane. The extreme values of these quantities are obtained for [110] and [1$\bar{1}$0] orientations of the dot. The width of singlet-triplet avoided crossing changes between these two orientations by as much as two orders of magnitude. The discussed modulation results from orientation-dependent strength of the Zeeman interaction which tends to polarize the spins in the direction of the external magnetic field and thus remove the spin-orbit coupling effects.