Synthesizing Weyl semimetals in weak topological insulator and topological crystalline insulator multilayers

We propose a different route to time-reversal invariant Weyl semimetals by employing multilayer heterostructures comprising ordinary "trivial" insulators and nontrivial insulators with pairs of protected Dirac cones on the surface. We consider both the case of weak topological insulators, where surface Dirac cones are pinned to time-reversal invariant momenta, and of topological crystalline insulators with unpinned surface Dirac cones. For both realizations we explain phenomenologically how the proposed construction leads to the emergence of a Weyl semimetal phase. We further formulate effective low-energy models for which we prove the existence of semimetallic phases with four isolated Weyl points. Finally, we discuss how the proposed design can be realized experimentally with state-of-the-art technologies.