Long-lived charged multiple-exciton complexes in strong magnetic fields

TL;DR

This paper investigates charged exciton complexes in a 2D electron-hole system under strong magnetic fields, revealing hidden symmetries that lead to infinite optical lifetimes and estimating their binding energies and recombination rates.

Contribution

It identifies a series of charged multiple-exciton states and analyzes their properties using variational and exact diagonalization methods, highlighting the role of hidden symmetry.

Findings

Bound states cannot be created by direct optical absorption due to hidden symmetry.

Once created, these states have an infinite optical recombination lifetime.

Recombination rates are estimated when symmetry is broken by layer displacement.

Abstract

We consider the charged exciton complexes of an ideal two-dimensional electron-hole system in the limit of strong magnetic fields. A series of charged multiple-exciton states is identified and variational and finite-size exact diagonalization calculations are used to estimate their binding energies. We find that, because of a hidden symmetry, bound states of excitons and an additional electron cannot be created by direct optical absorption and, once created, have an infinite optical recombination lifetime. We also estimate the optical recombination rates when electron and hole layers are displaced and the hidden symmetry is violated.