DATA: 10052017
SEZIONE DI FIRENZE Seminario teorico di Leda Bucciantini (Max Planck, Dresda)
Abstract:
When a Dirac semimetal is subject to a circularly polarized laser, it is predicted that the Dirac cone splits into two Weyl nodes and a nonequilibrium transient state called the Floquet Weyl semimetal is realized. We focus on the previously unexplored low frequency regime, where the upper and lower Dirac bands resonantly couples with each other through multiphoton processes, which is a realistic situation in solid stateÂ ultrafast pumpprobe experiments. We find a series of new Weyl nodes emerging in pairs when the Floquet replica bands hybridize with each other. The nature of the Floquet Weyl semimetal with regard
to the number, locations, and monopole charges of these Weyl nodes is highly tunable with the amplitude and frequency of the light. We derive an effective
low energy theory using BrillouinWigner expansion and further regularise the theory on a cubic lattice. The monopole charges obtained from the lowenergy Hamiltonian can be reconciled with the number of Fermi arcs on the lattice which we find numerically.
