Peculiarity of charge dynamics in high-Tc cuprates

Discussion is focused on the peculiarity of the out-of-plane and the in-plane charge dynamics related to the two-dimensionality in high-rr, cuprates. Recent observations of a double Josephson plasmon and a intra-bilayer Josephson effect remind us that each CuO2-plane is in fact an independent superconducting layer, suggesting that the superconducting coherence length in the c-direction is shorter than the interlayer distance. The origin of this extremely short c-axis coherence length as well as the long c-axis penetration depth is discussed in relation with the incoherent c-axis transport in the normal state. Another peculiarity is a strong itinerant nature of charges within the planes. As an example, it is demonstrated that a static charge order is inhibited even in the "stripe" phase in the cuprates. (C) 2000 Elsevier Science B.V. All rights reserved.