Hole doping dependences of the magnetic penetration depth and vortex core size in YBa2Cu3Oy: Evidence for stripe correlations near 1/8 hole doping

TL;DR

This study uses muon spin rotation to explore how hole doping affects magnetic penetration depth and vortex core size in YBa2Cu3Oy, revealing evidence for stripe correlations near 1/8 doping.

Contribution

It provides detailed doping-dependent measurements of magnetic and vortex properties, highlighting the enhancement near 1/8 doping and supporting stripe correlation theories.

Findings

Tc has a sublinear dependence on superfluid density.

Vortex core size increases with decreasing doping.

Enhanced properties near 1/8 doping suggest stripe correlations.

Abstract

We report on muon spin rotation measurements of the internal magnetic field distribution n(B) in the vortex solid phase of YBa2Cu3Oy (YBCO) single crystals, from which we have simultaneously determined the hole doping dependences of the in-plane Ginzburg-Landau (GL) length scales in the underdoped regime. We find that Tc has a sublinear dependence on 1/lambda_{ab}^2, where lambda_{ab} is the in-plane magnetic penetration depth in the extrapolated limits T -> 0 and H -> 0. The power coefficient of the sublinear dependence is close to that determined in severely underdoped YBCO thin films, indicating that the same relationship between Tc and the superfluid density is maintained throughout the underdoped regime. The in-plane GL coherence length (vortex core size) is found to increase with decreasing hole doping concentration, and exhibit a field dependence that is explained by proximity-induced superconductivity on the CuO chains. Both the magnetic penetration depth and the vortex core size are enhanced near 1/8 hole doping, supporting the belief by some that stripe correlations are a universal property of high-Tc cuprates.