Send to

Choose Destination
Phys Rev Lett. 2015 Sep 18;115(12):126803. doi: 10.1103/PhysRevLett.115.126803. Epub 2015 Sep 16.

Dirac Semimetals in Two Dimensions.

Author information

Center for Computational Materials Science, U.S. Naval Research Laboratory, Washington, D.C. 20375, USA.
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA.


Graphene is famous for being a host of 2D Dirac fermions. However, spin-orbit coupling introduces a small gap, so that graphene is formally a quantum spin Hall insulator. Here we present symmetry-protected 2D Dirac semimetals, which feature Dirac cones at high-symmetry points that are not gapped by spin-orbit interactions and exhibit behavior distinct from both graphene and 3D Dirac semimetals. Using a two-site tight-binding model, we construct representatives of three possible distinct Dirac semimetal phases and show that single symmetry-protected Dirac points are impossible in two dimensions. An essential role is played by the presence of nonsymmorphic space group symmetries. We argue that these symmetries tune the system to the boundary between a 2D topological and trivial insulator. By breaking the symmetries we are able to access trivial and topological insulators as well as Weyl semimetal phases.

Supplemental Content

Full text links

Icon for American Physical Society
Loading ...
Support Center