Optical studies of magnetic kagome metals: Effect of magnetism, localized carriers and phonons

Kagome metals attract a lot of attention as materials that combine two extreme features in their electronic structure: Massless Dirac fermions with linear band dispersion and flat bands hosting massive localized electrons. Topological nature of the former and strongly correlated nature of the latter lead to multitude of exotic phenomena, including quantum anomalous Hall effect and novel states, such as axion insulators. The electron dynamics of these systems is the key for understanding the proposed exotic phenomena including topological properties, strong electron correlations, and magnetism; along with the interplay of those.

To this end, we have employed optical spectroscopy on a series of kagome metals with different magnetic ground states. Interband and intraband transitions have been traced with broadband IR spectroscopy, where the signatures of itinerant and localized carriers have been identified. The relaxation dynamics of different contributions have also been investigated via ultrafast optical pump-probe spectroscopy. Moreover, the effect of underlying magnetic structure on the observed features and the behavior of the phonons have been discussed. In this talk, I summarize the optical fingerprints of unconventional features in magnetic kagome metals.