Multiorbital analysis of the effects of uniaxial and hydrostatic pressure on Tc in the single-layered cuprate superconductors

The origin of uniaxial and hydrostatic pressure effects on Tc in the single-layered cuprate superconductors is theoretically explored. A two-orbital model, derived from first principles and analyzed with the fluctuation exchange approximation gives axial-dependent pressure coefficients ∂Tc/∂Pa>0, ∂Tc/∂Pc<0, with a hydrostatic response ∂Tc/∂P>0 for both La214 and Hg1201 cuprates, in qualitative agreement with experiments. Physically, this is shown to come from a unified picture in which higher Tc is achieved with an “orbital distillation,” namely, the less the dx2-y2 main band is hybridized with the dz2 and 4s orbitals the higher the Tc. Some implications for obtaining higher Tc materials are discussed.