Charge segregation model for superconducting correlations in cuprates above $T_c$

TL;DR

This paper develops a theoretical model to explain TF-$b$SR experimental data in cuprates, proposing charge-ordered superconducting domains above $T_c$ and showing that Josephson-coupled domains better match observations.

Contribution

It introduces a charge segregation model with phase-coherent regions above $T_c$ and compares two scenarios for magnetic response, favoring Josephson coupling.

Findings

Josephson-coupled domains better fit experimental data

Charge-ordered regions exist above $T_c$ in cuprates

Model reproduces TF-$b$SR experimental features

Abstract

We present a theoretical framework for understanding recent transverse field muon spin rotation (TF-$\mu$SR) experiments on cuprate superconductors in terms of localized regions of phase-coherent pairing correlations above the bulk superconducting transition temperature $T_c$. The local regions of phase coherence are associated with a tendency toward charge ordering, a phenomenon found recently in hole-doped cuprates. We simulate the appearance of these regions by a conserved order parameter dynamics, and perform self-consistent superconducting calculations using the Bogoliubov-deGennes method. Within this context we explore two possible scenarios: (i) The magnetic field is diamagnetically screened by the sum of varying shielding currents of isolated small-sized superconducting domains. (ii) These domains become increasingly correlated by Josephson coupling as the temperature is lowered and the main response to the applied magnetic field is from the sum of all varying tunneling currents. The results indicate that these two approaches may be used to simulate the TF-$\mu$SR data but case (ii) yields better agreement.