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

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.