Role of two-dimensional electronic state in superconductivity inLa2−xSrxCuO4

Abstract

We have measured out-of-plane resistivity ${\ensuremath{\rho}}_{c}$ for ${\mathrm{La}}_{2\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{CuO}}_{4}$ under anisotropic pressure. c-axis compression, which decreases ${\ensuremath{\rho}}_{c},$ reduces ${T}_{\mathrm{c}}$ drastically, whereas c-axis extension, which increases ${\ensuremath{\rho}}_{c},$ enhances ${T}_{\mathrm{c}}$ from 38 K at ambient pressure to 51.6 K at 8 GPa. We find that the variation of ${T}_{\mathrm{c}}$ scales as a function of ${\ensuremath{\rho}}_{c},$ and that the c-axis pressure coefficient is much stronger than the $\mathrm{ab}$-axis one. These findings imply that ${T}_{\mathrm{c}}$ depends primarily on the interlayer, rather than the in-plane, lattice parameter.