Semimetallic and semiconducting graphene-hBN multilayers with parallel or reverse stacking

We theoretically investigate 3D layered crystals of alternating graphene and hBN layers with different symmetries. Depending on the hopping parameters between the graphene layers, we find that these synthetic 3D materials can feature semimetallic, gapped, or Weyl semimetal phases. Using first-principles calculations to parameterize the low-energy Hamiltonians we establish the most likely electronic phases. Our results demonstrate that 3D crystals stacked from individual 2D materials represent a new materials class with emergent properties different from their constituents.