Linewidths in excitonic absorption spectra of cuprous oxide

Abstract

We present a theoretical calculation of the absorption spectrum of cuprous oxide $\left({\mathrm{Cu}}_{2}\mathrm{O}\right)$ 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 ${\mathrm{Cu}}_{2}\mathrm{O}$ like the central-cell corrections for the $1S$ exciton allows us to calculate the experimentally observed linewidths in experiments by T. Kazimierczuk et al. [T. Kazimierczuk, D. Fr\"ohlich, S. Scheel, H. Stolz, and M. Bayer, Nature (London) 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.