Anisotropic pressure dependence of the critical temperature in YBa2Cu3O7: A picture for pressure effects in cuprates

The anisotropic pressure dependence of T-c in YBa2Cu3O7 is reproduced with self-consistent calculations without considering the chains or speculating pressure-induced charge transfers. Our approach is based on a pairing kerne l, which selects the small-q processes and could possibly reflect phonon me diated superconductivity in the presence of strong electron correlation. Th e ground state of our system has the basic characteristics of the supercond ucting state of YBa2Cu3O7 (dominantly d-wave gap) including the orthorhombi city effects. Following our analysis, we propose a simple classification sc heme for the hydrostatic pressure dependence of T-c in the cuprates, arguin g that pressure-induced charge transfers occur only in the underdoped mater ials due to the destruction by pressure of a competing to superconductivity order (possibly related to the pseudogap).