On the possibility that STS "gap-maps" of cuprate single crystals are dominated by k-space anisotropy and not by nano-scale inhomogeneity

TL;DR

This paper suggests that the spatial variations observed in STS measurements of cuprate superconductors may be due to k-space anisotropy inherent in d-wave pairing, rather than nanoscale inhomogeneity.

Contribution

It introduces a simple 2D quantum tunnelling model showing that STS gap variations can stem from k-space anisotropy, challenging the common interpretation of nanoscale inhomogeneity.

Findings

STS gap variations may be due to k-space anisotropy

The model links spatial dependence to momentum dependence

Potential to extract k-dependent info from STS data

Abstract

The results of a computer analysis of a simple 2D quantum mechanical tunnelling model are reported. These suggest that the spatial dependence of the superconducting energy gap observed by Scanning Tunnelling Spectroscopy (STS) studies of single crystals of the high Tc superconductor Bi:2212 is not necessarily caused by nanoscale inhomogeneity. Instead the spatial dependence of the STS data could arise from the momentum (k) dependence of the energy gap, which is a defining feature of a d-wave superconductor. It is possible that this viewpoint could be exploited to obtain k-dependent information from STS studies.