  Hole concentration in the CuO2 plane largely controls all the properties in
the normal and superconducting states of high-Tc cuprates. The critical current
density, Jc, is no exception. Previous hole content dependent studies have
demonstrated that the role of intrinsic depairing current density in
determining the observed critical current density in copper oxide
superconductors. It is also widely agreed upon that the temperature and
magnetic field dependent vortex pinning energy plays a major role the Jc of a
system.This pinning energy depends directly on the superconducting condensation
energy. Superconducting condensation energy, on the other hand, is proportional
to the Cooper pair density (superpair density), which is found to be highly
dependent on the hole concentration, p, within the CuO2 plane. We have
calculated the Cooper pair density, rho_s, of YBCO (Y123), a typical hole doped
cuprate, as a function of p, in this study. A triangular pseudogap (PG), pinned
at the Fermi level, in the quasiparticle spectral density has been considered.
The low-temperature critical current density of a number of Y(Ca)BCO
superconductors over wide range of compositions and hole concentrations have
been explored. The normalized values of the superpair density and the critical
current density exhibit a clear correspondence as the in-plane hole content is
varied. This systematic behavior provides us with strong evidence that the
critical current density of hole doped cuprates is primarily dependent on the
superpair density, which in turn depends on the magnitude of the PG energy.The
agreement between the estimated p-dependent superpair density and the
previously experimentally determined superfluid density of Y(Ca)BCO is quite
remarkable.
