# Dresden 2017 – wissenschaftliches Programm

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# DS: Fachverband Dünne Schichten

## DS 33: Transport: Topological Semimetals 2 (jointly with MA/TT)

### DS 33.7: Vortrag

### Mittwoch, 22. März 2017, 16:45–17:00, HSZ 204

**Emergent Weyl nodes and Fermi arcs in a Floquet Weyl semimetal** — •Leda Bucciantini^{1}, Stithadi Roy^{1}, Sota Kitamura^{2}, and Takashi Oka^{1} — ^{1}Max Planck Institute for Physics of Complex Systems, Germany — ^{2}Tokyo University, Japan

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 multi-photon processes, which is a realistic situation in solid state ultrafast pump-probe 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 Brillouin-Wigner expansion and further regularize the theory on a cubic lattice. The monopole charges obtained from the low-energy Hamiltonian can be reconciled with the number of Fermi arcs on the lattice which we find numerically.