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 kernel, which selects the small-q processes and could possibly reflect phonon mediated superconductivity in the presence of strong electron correlation. The ground state of our system has the basic characteristics of the superconducting state of YBa2Cu3O7 (dominantly d-wave gap) including the orthorhombicity effects. Following our analysis, we propose a simple classification scheme for the hydrostatic pressure dependence of T-c in the cuprates, arguing that pressure-induced charge transfers occur only in the underdoped materials due to the destruction by pressure of a competing to superconductivity order (possibly related to the pseudogap).