Ultrafast spectral weight transfer in RBaCo2O6−δ (R=Sm, Gd, and Tb): Role of electronic correlation in a photoinduced phase transition
Résumé
We performed femtosecond reflection spectroscopy on a series of A-site ordered perovskite-type cobalt oxide RBaCo2O6−δ (R=Sm, Gd, and Tb) crystals, in which the electronic transfer was controlled by R. The transient reflectivity and the optical conductivity [σPI(ω)] obtained by a Kramers-Kronig analysis showed an ultrafast change within a time resolution (≈150 fs) at room temperature and the appearance of signals of a hidden state that were different from the high-temperature metallic state. The transferred spectral weight in σPI(ω) upon photoexcitation sensitively depended on the R species, indicating an important role of electronic correlation in the photoexcited state.