Optical fingerprints of unconventional carriers in kagome metals

Kagome metals are the newly emerging class of quantum materials, where the peculiar kagome structure along with the itinerant character of the electrons give rise to a non-trivial combination of entangled magnetic states, electronic correlations, and topological orders. Two dissimilar features of massive, localized carriers at dispersionless flat bands and the massless Dirac fermions at the linearly dispersing bands coexist in their electronic structure, giving rise to various exotic phenomena. While the magnetic kagome metals are at the center of interest due to the proximity of the flatband magnetism, newly discovered non-magnetic counterparts possess a peculiar density wave order along with the unconventional superconductivity.

Optical spectroscopy is a useful method that shows excellent sensitivity to both linear and flat bands. Furthermore, (partial)gaps at the density of state at Fermi energy can be identified with clear signatures in optical spectra and the energy scale can be discussed. The opportunity to combine with other external stimuli such as magnetic field and pressure offers a viable route to disentangle different contributions. In this talk, I will highlight the optical fingerprints of unconventional carriers in these unique materials.