Type-II Weyl cone transitions in driven semimetals

TL;DR

This paper explores how circularly polarized light can induce and control type-II Weyl fermions in driven Dirac and line node semimetals, revealing new phase transition pathways and phase diagrams.

Contribution

It demonstrates the induction and tunability of type-II Weyl fermions in driven semimetals using circularly polarized light, expanding the understanding of Floquet topological phases.

Findings

Type-II Weyl fermions can be generated in driven Dirac and line node semimetals.

Weyl node pairs' types are controllable via drive amplitude and direction.

Phase diagrams suggest feasible experimental realization.

Abstract

Periodically driven systems provide tunable platforms to realize interesting Floquet topological phases and phase transitions. In electronic systems with Weyl dispersions, the band crossings are topologically protected even in the presence of time-periodic perturbations. This robustness permits various routes to shift and tilt the Weyl spectra in the momentum and energy space using circularly polarized light of sufficient intensity. We show that type-II Weyl fermions, in which the Weyl dispersions are tilted with the appearance of pocket-like Fermi surfaces, can be induced in driven Dirac semimetals and line node semimetals. Under a circularly polarized drive, both semimemtal systems immediately generate Weyl node pairs whose types can be further controlled by the driving amplitude and direction. The resultant phase diagrams demonstrate experimental feasibilities.