FLUCTUATION-INDUCED PSEUDOGAP IN HIGH-TEMPERATURE SUPERCONDUCTORS

We study the effect of fluctuations on the ac conductivity of a layere d superconductor for c-axis electromagnetic wave polarization. The flu ctuation contributions of different physical nature and sign (paracond uctivity, Maki-Thompson anomalous contribution, one-electron density-o f-states renormalization) are found to be suppressed by the external f ield at different characteristic frequencies (omega(AL)similar to T-T- c, omega(MT)similar to max{T-T-c,tau(phi)(-1)}, omega(DOS)similar to m in{T,tau(-1)}). As a result, the appearance of a nonmonotonic frequenc y dependence (pseudogap) in the infrared optical conductivity of high- temperature superconductor is predicted. (C) 1996 American Institute o f Physics.