Eigenenergies of excitonic giant-dipole states in cuprous oxide

TL;DR

This paper investigates the energy levels of giant-dipole excitons in cuprous oxide under crossed electric and magnetic fields, revealing conditions for their stability and providing detailed spectral calculations.

Contribution

It introduces a theoretical framework for calculating excitonic spectra in crossed fields, including both approximate and exact methods, and identifies the magnetic field strength necessary for stable giant-dipole states.

Findings

Stable giant-dipole excitons only form in strong magnetic fields.

Computed excitonic spectra with level spacings of 0.6 to 100 μeV.

Validated approximate methods against numerical calculations.

Abstract

In this work we present the eigenspectra of a novel species of Wannier excitons when exposed to crossed electric and magnetic fields. In particular, we compute the eigenenergies of giant-dipole excitons in $\textrm{Cu}_2\textrm{O}$ in crossed fields. In our theoretical approach, we calculate the excitonic spectra within both an approximate as well as a numerically exact approach for arbitrary field configurations. We verify that stable bound excitonic giant-dipole states are only possible in the strong magnetic field limit, as this is the only regime providing sufficiently deep potential wells for their existence. Comparing both analytic as well as numerical calculations, we obtain excitonic giant-dipole spectra with level spacings in the range of $0.6\ldots100\, \mu \textrm{eV}$.