Pseudogap and conduction dimensionalities in high-Tc superconductors

The nature of normal state charge-carriers' dynamics and the transition in conduction and gap dimensionalities between 2D and 3D for YBa2Cu3O7-delta and Bi2Sr2Ca1-xYxCu2O8 high-T-c superconductors were described by computing and fitting the resistivity curves, rho(T, delta, x). These were carried out by utilizing the 2D and 3D Fermi liquid and ionization energy (E-1) based resistivity models coupled with charge-spin separation based t-J model (Phys. Rev. B 64 (2001) 104516). rho(T, delta, x) curves of Y123 and Bi2212 samples indicate the beginning of the transition of conduction and gap from 2D to 3D with reduction in oxygen content (7 - delta) and Ca2+ (1 - x) as such, c-axis pseudogap could be a different phenomenon from superconductor and spin gaps. These models also indicate that the recent MgB2 superconductor is at least not Y123 or Bi2212 type. (C) 2002 Elsevier Science B.V. All rights reserved.