Interlayer excitons in double-layer transition metal dichalcogenides quantum dots

TL;DR

This paper investigates the properties of interlayer excitons in double-layer transition metal dichalcogenide quantum dots using analytical and numerical methods, revealing effects of magnetic fields, material stacking, and electron spins on exciton behavior.

Contribution

It introduces a comprehensive analysis of interlayer excitons in quantum dots, including magnetic field effects, material influences, and exciton interactions, with novel insights into topological textures and optical properties.

Findings

Landau level gap and exciton separation vary non-monotonously with interlayer distance in magnetic fields.

Exchange interaction enhances binding energy when electrons have different spins.

Optical spectra can distinguish electron spin states in excitons.

Abstract

Various properties of interlayer excitons in double-layer transition metal dichalcogenides quantum dots are analyzed using a low-energy effective Hamiltonian with Coulomb interaction. We solve the single-particle Hamiltonian with and without a magnetic field analytically, then present the electron-hole pairing features of interlayer exciton by employing the exact diagonalization technique, where the electron and hole are located in two layers respectively. In a magnetic field, the Landau level gap, as well as the electron-hole separation of an exciton varies non-monotonously as the interlayer distance increases, attributed to the pseudospin-orbit coupling which also leads to the emergence of topological non-trivial pseudospin textures in the exciton states. We examine the influence of different materials in quantum dots stacking on the exciton states, comparing their impact to variations in layer distances and quantum dot sizes. We further explore two interacting interlayer excitons numerically. The binding energy is significantly enhanced by the exchange interaction when the two electrons have different spins. The optical absorption spectra from the ground state to low-lying excited states reveal distinct behaviors for different interlayer excitons, which can be utilized to distinguish the spin of electrons in excitons. Our results highlight the potential for controlling interlayer excitons and applications of optical devices in a magnetic field and tunable layer distance.