Pseudogap-Like Phenomena in Cuprates as a Manifestation of Charge-Density Waves

Abstract

Differential conductance G as a function of the bias voltage V was measured for break-junctions of superconducting Bi2Sr2CaCu2O8+δ and YBa2Cu3O7−δ. The dependences G(V ) for both materials clearly demonstrate the so-called dip–hump structures outside the gap region. A theory, which suggests the charge-density-wave origin of the dip–hump structures and explains its specific form by intrinsic inhomogeneity of cuprate materials, was developed. The well-known pseudogap features in the tunnel spectra of high-Tc oxides found both below and above the superconducting critical temperature are also described by the theory, which testifies that both the pseudogap and the dip–hump structures have the same origin. Competing theories and various G(V ) peculiarities found for a number of superconducting oxides are briefly discussed.