Two-dimensional topological semimetal state in a nanopatterned semiconductor system

We propose the creation of a two-dimensional topological semimetal in a semiconductor artificial lattice with triangular symmetry. An in-plane magnetic field drives a quantum phase transition between the topological insulating and topological semimetal phases. The topological semimetal is characterized by robust band-touching points which carry quantized Berry flux and edge states which terminate at the band-touching points. The topological phase transition is predicted to occur at magnetic fields ∼4T in high mobility GaAs artificial lattices, and can be detected via the anomalous behavior of the edge conductance.