“Floquet-Bloch bands in Dirac and Weyl fermionic systems” by Ching-Kit Chan (UCLA)

Wednesday, October 5, 2016 - 4:00pm
Condensed Matter Physics Journal club Seminar

It is typically difficult to understand physical systems driven far away from equilibrium where the energy is not conserved. However, when a system is driven periodically in time, a well-defined quasi-Hamiltonian exists which permits equilibrium descriptions and fruitful concepts borrowed from condensed matter physics. The corresponding quasi-energies, known as the Floquet bands, are analogous to Bloch bands in lattice systems caused by spatial periodicity. In this talk, I will first review the current experimental situation on the observation of Floquet-Bloch bands by laser-driving 2D Dirac fermions on the surface of a topological insulator. I will then discuss various theoretical proposals of driving the 3D generalization---Weyl fermions in semimetal materials. We shall see how the coupling between chiral fermions and chiral photons can induce sizeable anomalous Hall conductivities and transitions among different topological semimetal phases. Our findings are accessible by transport and optical measurements.

PAB 4-330