Floquet higher-order Weyl and nexus semimetals
Weiwei Zhu, Muhammad Umer, Jiangbin Gong
Abstract
This work reports the general design and characterization of two exotic, anomalous nonequilibrium gapless topological phases. In equilibrium systems, the Weyl nodes or the crossing points of nodal lines of threedimensional systems 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 topological phases. Our theoretical results stimulate and guide future experiments on higher-order semimetal phases using, for example, a three-dimensional lattice of coupled ring resonators.