Hirofumi Sakakibara, Katsuhiro Suzuki, Hidetomo Usui, Kazuhiko Kuroki, Ryotaro Arita, Douglas J. Scalapino, Hideo Aoki
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, $\partial Tc=\partial P_a > 0$, $T_c=\partial P_c < 0$, with a hydrostatic response $\Partial T_c=\Partial P > 0$ for both La214 and Hg1201, 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 d_{x^{2}-y^{2}} main band is hybridized with the $d_{z^2}$ and $4s$ orbitals the higher $T_c$. Some implications for obtaining higher $T_c$ materials are discussed.
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http://arxiv.org/abs/1203.4353
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