PhotoWann · Bulk Photovoltaic effect via Wannier functions

PhotoWann aims to shed light into the exceptional properties related to the bulk photovoltaic effect (BPVE) - a nonlinear absorption process - of cutting edge materials like Weyl semimetals, whose photocurrent has very recently been measured to reach colossal values. Thanks to a newly developed method, the track record of the applicant and the expertise of the Host in this field, we are in a privileged position for quantitatively accessing the structure of the BPVE that emerges from narrow k-space regions surrounding the Weyl points, hence shedding light into the breakthrough experimental measurements as well as proposing novel ones. As an additional major goal for the project, we will perform a combined theoretical-experimental investigation (secondment) with the group of T. Neupert in UZH Zurich for analyzing the beta phase of GeSe, a newly synthesized 2D material that is expected to show unconventional nonlinear absorption properties thanks, among other features, to its unusually large electronic density of states, making it a realistic candidate for future applications. In parallel with these two major objectives, we plan to undertake yet another ambitious goal, namely the development and implementation of a robust and efficient computational algorithm for the calculation of the various properties related to the BPVE within the well-established free-software package WANNIER90. This will undoubtedly benefit a substantial part of the scientific community in this field, as it will turn the up-to-now cumbersome and almost prohibitive calculation of this type of processes into a fairly routine task. Our work will therefore generate a fundamental and systematic understanding of nonlinear physics of solids not only through our particular investigations, but also from many other researcher's via the developed and shared computational algorithm.