Pseudogap phenomena in high-T-c cuprates as a precursor of the strong coupling superconductivity

We point out that the pseudogap phenomena observed in under-doped High-T-c cuprates are naturally understood as a precursor of the strong coupling sup erconductivity. A strong coupling superconductivity necessarily leads to st rong fluctuations. In particular, the superconducting fluctuations, which a re strongly diffusive within the conventional weak coupling theory, become propagative and have a character of the pre-formed pairs in the strong coup ling case. Such strong fluctuations lead to the gap structure of both the s pectral weight and the density of states. The superconducting critical temp erature is strongly reduced by the fluctuations in the strong coupling case . (C) 2000 Published by Elsevier Science B.V. All rights reserved.