Numerical Investigation of Triexciton Stabilization in Diamond with Multiple Valleys and Bands

TL;DR

This study numerically demonstrates the stability of various excitonic complexes, including triexcitons, in diamond, accounting for multiple valleys and bands, and aligns well with experimental binding energies.

Contribution

It introduces a comprehensive numerical approach that confirms the stability of polyexcitons in diamond considering complex band and valley structures.

Findings

Triexcitons are stable in diamond.

Numerical binding energies match 81-86% of experimental values.

Multiple valleys and bands are crucial for stability analysis.

Abstract

The existence of polyexcitons, the $N$-body complexes of excitons for $N > 2$ in 3D bulk systems, has been controversial for more than 40 years since its first theoretical suggestion. We investigated the stability of fundamental excitonic complexes in diamond numerically with the stochastic variational method (SVM) and an explicitly correlated Gaussian (ECG) basis. The electron-hole many-body system is described by an effective mass Hamiltonian. Our model includes the effective mass anisotropy and multiple valley and band degrees of freedom. We show that the excitons, trions, biexcitons, charged biexcitons, and triexcitons are stable in diamond. Numerical calculations reproduce from 81% to 86% of the experimentally reported binding energies for neutral bound states.