Generic coexistence of Fermi arcs and Dirac cones on the surface of time-reversal invariant Weyl semimetals

Alexander Lau, Jeroen van den Brink, Carmine Ortix

Published 2017-01-06Version 1

The hallmark of Weyl semimetals is the existence of open constant-energy contours on their surface -- the so-called Fermi arcs -- connecting Weyl points. Here, we show that for time-reversal symmetric realizations of Weyl semimetals these Fermi arcs generically coexist with closed Fermi pockets originating from surface Dirac cones pinned to time-reversal invariant momenta. The existence of Fermi pockets is required for certain Fermi-arc connectivities due to additional restrictions imposed by the six $\mathbb{Z}_2$ topological invariants characterizing a generic time-reversal invariant Weyl semimetal. We show that a change of the Fermi-arc connectivity generally leads to a different topology of the surface Fermi surface, which is regulated by a Lifshitz transition. We further identify universal features of this coexistence in quasi-particle interference spectra that are experimentally accessible by scanning-tunneling spectroscopy.