Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Kagome metals possess a peculiar optical spectrum consisting of contributions from free charge carriers, localized carriers seen as a strongly temperature-dependent localization peak, and, in some cases, phonons displaying strong anomalies. The magnetic rare-earth kagome metal series, ReMn₆Sn₆, provides a marvelous playground to study the electronic properties of kagome metals in the presence of magnetism. Here, we report temperature-dependent reflectivity studies on two members of the ReMn₆Sn₆ family, GdMn₆Sn₆ (in-plane ferrimagnet) and TbMn₆Sn₆ (out-of-plane ferrimagnet), in a broad energy range (50 -18000 cm$^{-1}$, equivalent to 6 meV - 2.25 meV) down to 10 K. At high temperatures, a phonon mode at 160 cm$^{-1}$ is observed, which becomes screened out in TbMn₆Sn₆ below 150 K as the localization peak linearly passes through the mode. In GdMn₆Sn₆, the disappearance of the phonon is accompanied by the onset of saturation of the peak position, suggesting an unusual interplay between the two features. Lastly, our calculations reveal the strongly correlated nature of ReMn₆Sn₆ compounds and hence, significant deviations from the simple band picture.