Probing electron topology with Raman scattering

Nodal electron spectrum is a characteristic feature of many topological quantum materials, still difficult to experimentally determine and probe. When topology protects the nodes, the low-energy nodal spectrum is distinguished from conventional spectra by its relativistic density of states. Here we review the recent progress in observing and measuring the properties of Weyl electrons with Raman scattering, and argue that, despite being a zero-momentum probe, Raman scattering is a sensitive detector of Weyl electrons capable of extracting the Fermi energy, Fermi momentum and even estimating the Weyl electron lifetime shaped by interactions and disorder. The utility of Raman scattering for the detection of quadratic band touching is also discussed.