Signatures of Weyl semimetals in quasiparticle interference

Abstract

Impurities act as in situ probes of nontrivial electronic structure, causing real-space modulations in the density of states detected by scanning tunneling spectroscopy on the sample surface. We show that distinctive features of Weyl semimetals can be revealed in the Fourier transform of this map which can be interpreted in terms of quasi-article interference (QPI). We develop an exact Green's function formalism and apply it to generalized models of Weyl semimetals with an explicit surface. The type of perturbation lifting the Dirac node degeneracy to produce the 3D bulk Weyl phase determines the specific QPI signatures appearing on the surface. For separated point nodes, QPI Fermi arcs may or may not appear, depending on the relative surface orientation; while line nodes give rise to tube projections of width controlled by the bias voltage. We also consider the effect of crystal warping, distinguishing dispersive arc-like features from true Fermi arcs.