Flux line lattice state versus magnetism in electron-doped cuprate superconductor Sr_{1-x}La_{x}CuO_{2}

TL;DR

This study investigates the flux line lattice and magnetic properties of electron-doped cuprate Sr_{1-x}La_{x}CuO_{2} using muon spin rotation, revealing phase separation, high superfluid density, and weak anisotropy, indicating a different superconducting class from hole-doped cuprates.

Contribution

The paper provides microscopic insights into flux line lattice behavior and magnetic phase separation in electron-doped cuprates, highlighting differences from hole-doped counterparts.

Findings

Phase separation between magnetic and non-magnetic phases.

Large superfluid density indicating a large Fermi surface.

Weak anisotropy in the superconducting order parameter.

Abstract

The microscopic details of flux line lattice state studied by muon spin rotation is reported in an electron-doped high-$T_{\rm c}$ cuprate superconductor, Sr$_{1-x}$La$_{x}$CuO$_{2}$ (SLCO, $x=0.10$--0.15). A clear sign of phase separation between magnetic and non-magnetic phases is observed, where the effective magnetic penetration depth [$\lambda\equiv\lambda(T,H)$] is determined selectively for the latter phase. The extremely small value of $\lambda(0,0)$ %versus $T_{\rm c}$ and corresponding large superfluid density ($n_s \propto \lambda^{-2}$) is consistent with presence of a large Fermi surface with carrier density of $1+x$, which suggests the breakdown of the "doped Mott insulator" even at the "optimal doping" in SLCO. Moreover, a relatively weak anisotropy in the superconducting order parameter is suggested by the field dependence of $\lambda(0,H)$. These observations strongly suggest that the superconductivity in SLCO is of a different class from hole-doped cuprates.