We compute valley splittings in Si/SiGe superlattices using ab initio density functional theory (DFT). This first-principle approach is expected to provide an excellent description of interfaces, strains, and atomistic disorder without empirically fitted parameters. We benchmark atomistic tight-binding (TB) and the ``2k0'' theory within the effective mass (EM) approximation against DFT. We show that DFT supports the main conclusions of the 2k0 theory, but reveals some limitations of semi-empirical methods such as the EM and TB, in particular about the description of atomistic disorder. The DFT calculations also highlight the effects of strong valley-orbit mixing at large valley splittings. Nevertheless, TB and the 2k0 theory shall provide reasonable valley splitting statistics in many heterostructures of interest for spin qubit devices.
@article{arxiv.2512.04879,
title = {Valley Splittings in Si/SiGe Heterostructures from First Principles},
author = {Lukas Cvitkovich and Tancredi Salamone and Christoph Wilhelmer and Biel Martinez and Tibor Grasser and Yann-Michel Niquet},
journal= {arXiv preprint arXiv:2512.04879},
year = {2025}
}