Fourier transform spectroscopy of d-wave quasiparticles in the presence of atomic scale pairing disorder

TL;DR

This study uses Fourier transform spectroscopy to analyze d-wave quasiparticles in BSCCO, revealing how atomic-scale pairing disorder influences quasiparticle interference patterns and resolves previous discrepancies between theory and experiment.

Contribution

It introduces a realistic model of out-of-plane disorder that explains experimental quasiparticle interference features in BSCCO.

Findings

Weak extended potential scatterers suppress large-momentum features.

Scattering at order parameter variations enhances dispersing q1-peaks.

The model aligns theoretical predictions with experimental observations.

Abstract

The local density of states power spectrum of optimally doped Bi$_2$Sr$_2$CaCu$_2$O$_{8+x}$ (BSCCO) has been interpreted in terms of quasiparticle interference peaks corresponding to an "octet'' of scattering wave vectors connecting k-points where the density of states is maximal. Until now, theoretical treatments have not been able to reproduce the experimentally observed weights and widths of these "octet'' peaks; in particular, the predominance of the dispersing "q$_1$'' peak parallel to the Cu-O bond directions has remained a mystery. In addition, such theories predict "background'' features which are not observed experimentally. Here, we show that most of the discrepancies can be resolved when a realistic model for the out-of-plane disorder in BSCCO is used. Weak extended potential scatterers, which are assumed to represent cation disorder, suppress large-momentum features and broaden the low-energy "q$_7$''-peaks, whereas scattering at order parameter variations, possibly caused by a dopant-modulated pair interaction around interstitial oxygens, strongly enhances the dispersing "q$_1$''-peaks.