Anomalous superconducting properties at magic doping levels in under-doped La2-xSrxCuO4 single crystals

TL;DR

This study investigates superconducting properties at specific doping levels in La2-xSrxCuO4 crystals, revealing anomalies near certain 'magic' doping values and discussing their implications for charge inhomogeneity and phase separation.

Contribution

It provides new insights into the doping-dependent superconducting behavior and identifies anomalous properties at specific 'magic' doping levels in under-doped La2-xSrxCuO4.

Findings

Sharp superconducting transitions near x=1/16 and x=1/9

Minimum Meissner fraction near x=1/9

Intrinsic properties related to charge inhomogeneity

Abstract

A series of high-quality under-doped La2-xSrxCuO4 superconductor crystals with x = 0.063 - 0.125 were prepared by traveling-solvent floating-zone (TSFZ) technique. We found by dc magnetic measurements that, in this series of crystals, the superconducting transition was quite sharp in the vicinity of the hole densities of x = 1/16 and x = 1/9 while it was much broader away from these two "magic numbers", and the Meissner fraction showed a remarkable minimum near x = 1/9. We concluded that these phenomena are reflections of intrinsic properties of this cuprate system. Our observations are discussed in light of recently proposed composite charge model together with charge inhomogeneity and electronic phase separations.