Floquet higher-order Weyl and nexus semimetals

TL;DR

This paper introduces a novel method to realize Floquet higher-order Weyl and nexus semimetals using time-sequenced insulator phases, revealing new topological phases with potential experimental implementations.

Contribution

It presents a strategy to generate exotic Floquet topological phases solely from normal insulator phases, expanding the understanding of nonequilibrium topological matter.

Findings

Discovery of Floquet higher-order Weyl semimetals

Proposal for experimental realization with coupled ring resonators

Identification of new topological phases in 3D Brillouin zone

Abstract

This work reports the general design and characterization of two exotic, anomalous nonequilibrium topological phases. In equilibrium systems, the Weyl nodes or the crossing points of nodal lines may become the transition points between higher-order and first-order topological phases defined on two-dimensional slices, thus featuring both hinge Fermi arc and surface Fermi arc. We advance this concept by presenting a strategy to obtain, using time-sequenced normal insulator phases only, Floquet higher-order Weyl semimetals and Floquet higher-order nexus semimetals, where the concerned topological singularities in the three-dimensional Brillouin zone border anomalous two-dimensional higher-order Floquet phases. The fascinating topological phases we obtain are previously unknown and can be experimentally studied using, for example, a three-dimensional lattice of coupled ring resonators.