Theory of spin, electronic and transport properties of the lateral triple quantum dot molecule in a magnetic field

TL;DR

This paper develops a theoretical framework for understanding the spin, electronic, and transport behaviors of a triple quantum dot molecule in a magnetic field, revealing controllable spin states and phase transitions.

Contribution

It introduces a generalized Hubbard model combined with LCHO-CI methods to analyze magnetic field effects on quantum dot spectra and spin states.

Findings

Observation of Aharonov-Bohm oscillations in spectra

Magnetic field control of spin degeneracies and transitions

Identification of spin phase transitions and spin blockade effects

Abstract

We present a theory of spin, electronic and transport properties of a few-electron lateral triangular triple quantum dot molecule in a magnetic field. Our theory is based on a generalization of a Hubbard model and the Linear Combination of Harmonic Orbitals combined with Configuration Interaction method (LCHO-CI) for arbitrary magnetic fields. The few-particle spectra obtained as a function of the magnetic field exhibit Aharonov-Bohm oscillations. As a result, by changing the magnetic field it is possible to engineer the degeneracies of single-particle levels, and thus control the total spin of the many-electron system. For the triple dot with two and four electrons we find oscillations of total spin due to the singlet-triplet transitions occurring periodically in the magnetic field. In the three-electron system we find a transition from a magnetically frustrated to the spin-polarized state. We discuss the impact of these phase transitions on the addition spectrum and the spin blockade of the lateral triple quantum dot molecule.