Linewidths in excitonic absorption spectra of cuprous oxide

TL;DR

This paper provides a theoretical calculation of the excitonic absorption spectrum in cuprous oxide, incorporating phonons and exciton properties, successfully matching experimental linewidths and discussing remaining discrepancies.

Contribution

It introduces an improved theoretical model for excitonic linewidths in Cu2O, including phonons and exciton-specific effects, aligning closely with experimental data.

Findings

Calculated linewidths match experimental observations within the same order of magnitude.

Inclusion of both acoustic and optical phonons improves theoretical accuracy.

Discussion of residual discrepancies highlights effects beyond current models.

Abstract

We present a theoretical calculation of the absorption spectrum of cuprous oxide $\left(\mathrm{Cu_{2}O}\right)$ based on the general theory developed by Y. Toyozawa. An inclusion not only of acoustic phonons but also of optical phonons and of specific properties of the excitons in $\mathrm{Cu_{2}O}$ like the central-cell corrections for the $1S$-exciton allows us to calculate the experimentally observed line widths in experiments by T. Kazimierczuk et al [Nature 514, 343, (2014)] within the same order of magnitude, which demonstrates a clear improvement in comparison to earlier work on this topic. We also discuss a variety of further effects, which explain the still observable discrepancy between theory and experiment but can hardly be included in theoretical calculations.