Interlayer excitons in double-layer transition metal dichalcogenide quantum dots

Various properties of interlayer excitons in double-layer transition metal dichalcogenide quantum dots are analyzed using a low-energy effective Hamiltonian with Coulomb interaction. We analytically solve the single-particle Hamiltonian with and without a magnetic field, then present the electron-hole pairing features of interlayer excitons 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 nonmonotonously as the interlayer distance increases, which is attributed to the pseudo-spin-orbit coupling that also leads to the emergence of topological nontrivial 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.