Optical conductivity in the CuO double chains of PrBa2Cu4O8:: Consequences of charge fluctuation -: art. no. 012502

We calculate the optical conductivity of CuO double chains of PrBa2Cu4O8 by the mean-field approximation for a coupled two-chain Hubbard model around quarter-filling. We show that the similar to40-meV peak structure, spectral shape, and small Drude weight observed in experiment are reproduced well by the present calculation, provided that the stripe-type charge ordering is present. We argue that the observed anomalous optical response may be due to the presence of stripe-type fluctuations of charge carriers in the CuO double chains; the fast time scale of the optical measurement should enable one to detect slowly fluctuating order parameters as virtually a long-range order.