Multiorbital analysis of the effects of uniaxial and hydrostatic pressure on<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>T</mml:mi><mml:mi>c</mml:mi></mml:msub></mml:math>in the single-layered cuprate superconductors

The origin of uniaxial and hydrostatic pressure effects on ${T}_{c}$ 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 $\ensuremath{\partial}{T}_{c}/\ensuremath{\partial}{P}_{a}&gt;0$, $\ensuremath{\partial}{T}_{c}/\ensuremath{\partial}{P}_{c}&lt;0$, with a hydrostatic response $\ensuremath{\partial}{T}_{c}/\ensuremath{\partial}P&gt;0$ for both La214 and Hg1201 cuprates, in qualitative agreement with experiments. Physically, this is shown to come from a unified picture in which higher ${T}_{c}$ is achieved with an ``orbital distillation,'' namely, the less the ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ main band is hybridized with the ${d}_{{z}^{2}}$ and $4s$ orbitals the higher the ${T}_{c}$. Some implications for obtaining higher ${T}_{c}$ materials are discussed.

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