Université Lyon 1,
21 av. Claude Bernard,
In this talk, I will review the physics of excitations obeying a Dirac equation in various crystals such as graphene (honeycomb lattice) or artificial crystals made, for example, of cold atoms in optical lattices or microwaves in arrays of dielectric resonators. Dirac excitations usually appear in the vicinity of contact points between two energy bands. These contact points can be described as topological defects and as such they carry a topological charge, often related to a Berry phase, that describes there annihilation/creation properties. We will show how this behavior has been recently probed in various physical realizations.
Work done in collaboration with Gilles Montambaux, Frédéric Piéchon and Lih-King Lim.