Biexcitons in two-dimensional systems with spatially separated electrons and holes

TL;DR

This paper investigates the properties of two-dimensional indirect biexcitons, analyzing their binding energies and wavefunctions through analytical and numerical methods, and identifies conditions for their stability based on layer separation.

Contribution

It provides a comprehensive analysis of the stability and binding energies of 2D indirect biexcitons, including critical layer separation thresholds and comparison of different computational techniques.

Findings

Stable biexcitons exist only below a critical interlayer distance.

Numerical binding energies agree with analytical asymptotics.

Threshold separation and uncertainties are estimated.

Abstract

The binding energy and wavefunctions of two-dimensional indirect biexcitons are studied analytically and numerically. It is proven that stable biexcitons exist only when the distance between electron and hole layers is smaller than a certain critical threshold. Numerical results for the biexciton binding energies are obtained using the stochastic variational method and compared with the analytical asymptotics. The threshold interlayer separation and its uncertainty are estimated. The results are compared with those obtained by other techniques, in particular, the diffusion Monte-Carlo method and the Born-Oppenheimer approximation.