Local density of states of a d-wave superconductor with inhomogeneous antiferromagnetic correlations

TL;DR

This study models the local density of states in a d-wave superconductor with inhomogeneous antiferromagnetic correlations, revealing a crossover from disordered to more homogeneous states and explaining experimental spectral features.

Contribution

It introduces a mean-field model capturing coexistence and inhomogeneity of superconducting and antiferromagnetic orders in doped cuprates.

Findings

Robust d-wave gap in the density of states

Suppression of coherence peaks with increased antiferromagnetic correlations

Distinct spectra of nanoscale antiferromagnetic domains

Abstract

The tunneling spectrum of an inhomogeneously doped extended Hubbard model is calculated at the mean field level. Self-consistent solutions admit both superconducting and antiferromagnetic order, which coexist inhomogeneously because of spatial randomness in the doping. The calculations find that, as a function of doping, there is a continuous cross over from a disordered ``pinned smectic'' state to a relatively homogeneous d-wave state with pockets of antiferromagnetic order. The density of states has a robust d-wave gap, and increasing antiferromagnetic correlations lead to a suppression of the coherence peaks. The spectra of isolated nanoscale antiferromagnetic domains are studied in detail, and are found to be very different from those of macroscopic antiferromagnets. Although no single set of model parameters reproduces all details of the experimental spectrum in BSCCO, many features, notably the collapse of the coherence peaks and the occurence of a low-energy shoulder in the local spectrum, occur naturally in these calculations.