Pseudogap-like phenomena in cuprates as a manifestation of charge-density waves

Differential conductance G as a function of the bias voltage V was measured for break-junctions of superconducting Bi2Sr2CaCu2O8+delta and YBa2Cu3O7-delta. 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-T-c 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.