Quasiparticle interference in temperature dependent-STM as a probe of superconducting coherence

Abstract

In this proceeding we explore the behavior of the quasiparticle interference pattern (QPI) of scanning tunneling microscopy in moderately underdoped cuprates as a function of temperature, T. After ensuring a minimal consistency with angle-resolved photoemission spectroscopy (ARPES), we find that the QPI pattern is profoundly sensitive to quasiparticle coherence and that it manifests two energy gap scales. In particular, we show that the superconducting QPI pattern vanishes at the same temperature as that at which the Fermi arcs appear. Experimental support for this conclusion comes from the observation of a nearly dispersionless QPI pattern which appears above Tc in moderately underdoped cuprates. To illustrate the important two energy scale physics we present predictions of the QPI-inferred energy gaps as a function of T in moderately underdoped cuprates. This defines the so-called “Bogoliubov arcs”, which possess an extinction point which is controlled by the size of the superconducting order parameter. A second larger energy scale is obtained by extrapolating the low-energy gap to the antinodes, presuming a simple d-wave shape. The validity of this extrapolation procedure is supported by our analysis of the ARPES gap and reveals the pseudogap energy scale.