Role of two-dimensional electronic state in superconductivity in La$_{2-x}$Sr$_{x}$CuO$_{4}$

TL;DR

This study investigates how changes in the c-axis lattice parameter affect the superconducting transition temperature in La$_{2-x}$Sr$_{x}$CuO$_{4}$, highlighting the importance of interlayer coupling for superconductivity.

Contribution

It demonstrates that $T_{c}$ in La$_{2-x}$Sr$_{x}$CuO$_{4}$ is primarily influenced by interlayer (c-axis) lattice modifications rather than in-plane changes, through resistivity measurements under anisotropic pressure.

Findings

c-axis compression decreases $T_{c}$ and reduces $ ho_c$

c-axis extension increases $T_{c}$ up to 51.6K at 8GPa

$T_{c}$ variation scales with $ ho_c$ and c-axis pressure has a stronger effect

Abstract

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