  We propose a model for high-Tc superconductors that includes both the spin
fluctuations of the Cu++ magnetic ions and of the spins of O-- doped holes
(spinons). The charge of the dopants (holons) is associated to quantum skyrmion
excitations of the Cu++ spin background. The quantum skyrmion effective
interaction potential is evaluated as a function of doping and temperature,
indicating that Cooper pair formation is determined by the competition between
these two types of spin fluctuations. The superconducting transition occurs
when the effective potential allows for skyrmion bound states. Our theoretical
predictions for the superconducting phase diagram of LSCO and YBCO are in good
agreement with experiment.
