Ultrafast Dynamics of Photoinduced Electronic Phase Modulation in Ladder Cuprate of Sr14-xCaxCu24O41

R. Fukayaa, b, M. Kunitomoa, Y. Okimotoa, T. Ishikawaa, K. Ondac, S. Koshiharaa, b, H. Yuid and T. Sasagawad aCREST, Japan Science and Technology Agency (JST), Meguro-ku, Tokyo 152-8551, Japan bDepartment of Materials Science, Tokyo Institute of Technology, Megro-ku, Tokyo 152-8551, Japan cDepartment of Environmental Chemistry and Engineering, Tokyo Institute of Technology, Yokohama Kanagawa 226-8502, Japan dMaterials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan

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Ultrafast carrier dynamics caused by photoexcitation in quasi-one-dimensional two-leg ladder cuprate Sr4Ca10Cu24O41 was investigated by the femtosecond reflection spectroscopy. After the photoexcitation along the leg direction, the transient reflectivity changes (ΔR/R) in the mid-infrared region showed instant decrease within 150 fs. The suppressed ΔR/R increased so rapidly on the picosecond time scale that the reflectivity value finally became larger than that in the initial state. Such a successive response in ΔR/R, which was also observed in other photon energy regions, is discussed in terms of ultrafast variation of the Drude weight in the ladder system by the photoirradiation.

DOI: 10.12693/APhysPolA.121.310 PACS numbers: 78.47.-p, 74.72.-h, 78.20.-e