Interacting holes in gated WSe$_2$ quantum dots

TL;DR

This paper develops a detailed atomistic theory for the electronic properties of holes in gated WSe$_2$ quantum dots, revealing how many-body interactions influence spin and valley states and induce phase transitions.

Contribution

It introduces a multi-scale, ab-initio based model combining tight-binding and configuration interaction techniques to study up to 6 holes in WSe$_2$ quantum dots with atomistic detail.

Findings

N=2 holes are in a valley and spin anti-ferromagnetic ground state

Higher hole numbers can lead to spontaneous valley and spin polarization

Quantum dot size and potential depth affect many-body phase transitions

Abstract

We develop here a theory of the electronic properties of a finite number of valence holes in gated WSe$_2$ quantum dots, considering the influence of spin, valley, electronic orbitals, and many-body interactions. The single-particle wave functions are constructed by combining the spin-up and down states of the highest valence bulk bands employing a multi-million atom ab-initio based tight-binding model solved in the wave-vector space, allowing to study up to 100 nm radius quantum dots atomistically. The effects of the many-body interactions are determined using the configuration interaction (CI) technique, applied up to $N = 6$ holes occupying up to 6 electronic shells with 42 orbitals. Our results show that N=2 holes are in valley and spin anti-ferromagnetic ground state, independent of the interaction strength and the quantum dot size. However, we predict that higher number of holes can undergo a transition to spontaneously broken symmetry valley and spin polarized ferromagnetic phases, highlighting the interplay between the many-body effects and the quantum dot lateral size and confining potential depth.