Fluctuation-induced pseudogap in high-temperature superconductors

Abstract

We study the effect of fluctuations on the ac conductivity of a layered superconductor for c-axis electromagnetic wave polarization. The fluctuation contributions of different physical nature and sign (paraconductivity, Maki-Thompson anomalous contribution, one-electron density-of-states renormalization) are found to be suppressed by the external field at different characteristic frequencies (ωAL∼T-Tc, ωMT∼max{T-Tc,τϕ−1}, ωDOS∼min{T, τ−1}). As a result, the appearance of a nonmonotonic frequency dependence (pseudogap) in the infrared optical conductivity of high-temperature superconductor is predicted.