High Tc copper oxides:: A theoretical view from Mott insulators

The conducting state of high T-c cuprates is realized in proximity to the Mott insulators (to be precise the insulating state of charge-transfer type), i.e. in the doped Mott insulators, and their transport and magnetic properties show various anomalies and the conducting state is then called the anomalous metallic state (AMS). Key experimental factors of this AMS are summarized briefly with special emphasis on the spin-gap phenomena. These features are theoretically analyzed based on the slave-boson mean-field approximation to the t-J model and then the effects of fluctuations around these mean-held solutions, treated as gauge fields, are discussed. It is seen that the present theoretical approach will be a first step towards the coherent understanding of the mysterious properties of AMS of doped Mott insulators. (C) 1998 Elsevier Science Ltd. All rights reserved.