Extinction of quasiparticle scattering interference due to nanoscale gap inhomogeneities in d-wave superconductors

Abstract

It is known that quasiparticle scattering interference (QPI) in underdoped cuprates ceases to be observed when the bias voltage is raised above a critical value, beyond which the dispersing, peak-like patterns seen at low energies become non-dispersing and static. In this paper, we explore the connection between QPI extinction and the presence of patchy gap inhomogeneities seen in STM experiments, employing large-scale simulations of an inhomogeneous d-wave superconductor. Making use of a simple model of a nanoscale-size gap patch within which a pointlike impurity is present, we find that the characteristic QPI signal expected from a homogeneous d-wave superconductor is captured well by the gap-patch model up until a characteristic energy, at which the QPI signal becomes markedly dissimilar relative to that expected from the homogeneous case.