  Weyl semimetals constitute a newly discovered class of three-dimensional
topological materials with linear touchings of valence and conduction bands in
the bulk. The most striking property of topological origin in these materials,
so far unequivocally observed only in photoemission experiments, is the
presence of open constant-energy contours at the boundary --- the so-called
Fermi arcs. In this work, we establish the universal characteristics of
Fermi-arc contributions to surface quasiparticle interference. Using a general
phenomenological model, we determine the defining interference patterns
stemming from the existence of Fermi arcs in a surface band structure. We then
trace these patterns in both simple tight-binding models and realistic ab
initio calculations. Our results show that definitive signatures of Fermi arcs
can be observed in existing and proposed Weyl semimetals using scanning
tunneling spectroscopy.
