Experimental evidence of chemical-pressure-controlled superconductivity in cuprates

TL;DR

This study demonstrates that chemical pressure, induced by cation substitution, significantly influences superconductivity in cuprates, independent of hole doping levels, highlighting the importance of lattice structure in superconducting behavior.

Contribution

It provides direct experimental evidence that chemical pressure controls superconductivity in cuprates, separate from charge doping effects.

Findings

Superconducting transition temperature (Tc) varies significantly with chemical pressure.

Doped hole concentration remains nearly constant despite changes in chemical pressure.

Lattice structure changes correlate with variations in superconducting properties.

Abstract

X-ray absorption spectroscopy (XAS) and high resolution X-ray diffraction are combined to study the interplay between electronic and lattice structures in controlling the superconductivity in cuprates with a model charge-compensated CaxLa1-xBa1.75-xLa0.25+xCu3Oy (0<x<0.5, y=7.13) system. In spite of a large change in Tc, the doped holes, determined by the Cu L and O K XAS, hardly show any variation with the x. On the other hand, the CuO2 plaquette size shows a systematic change due to different size of substituted cations. The results provide a direct evidence for the chemical pressure being a key parameter for controlling the superconducting ground state of the cuprates.