Nonlinear response signatures are increasingly recognized as useful probes of condensed matter systems, in particular for characterisation of topologically non-trivial states. The circular photogalvanic effect (CPGE) is particularly useful in study of topological semimetals, as the CPGE tensor quantises for well-isolated topological degeneracies in strictly linearly-dispersing band structures. Here, we study multiplicative Weyl semimetal band-structures, and find that the multiplicative structure robustly protects the quantization of the CPGE even in the case of non-linear dispersion. Computing phase diagrams as a function of Weyl node tilting, we find a variety of quantised values for the CPGE tensor, revealing that the CPGE is also a useful tool in detecting and characterising parent topology of multiplicative topological states.
@article{arxiv.2312.03159,
title = {Robust quantisation of circular photogalvanic effect in multiplicative topological semimetals},
author = {Adipta Pal and Dániel Varjas and Ashley M. Cook},
journal= {arXiv preprint arXiv:2312.03159},
year = {2025}
}