Realistic Floquet semimetal with exotic topological linkages between arbitrarily many nodal loops

TL;DR

This paper proposes a feasible periodic driving scheme to create and control complex linked nodal loops in Floquet semimetals, revealing new exotic topological phases with potential unique transport properties.

Contribution

It introduces a realistic method to generate arbitrarily many linked nodal loops in Floquet semimetals using accessible experimental parameters.

Findings

Arbitrarily many linked nodal loops can be realized through periodic driving.

Topological invariants like Berry phase and Alexander polynomial characterize linkages.

The scheme is experimentally feasible in quantum materials or cold atom systems.

Abstract

Valence and conduction bands in nodal loop semimetals (NLSMs) touch along closed loops in momentum space. If such loops can proliferate and link intricately, NLSMs become exotic topological phases with unconventional topological characteristics and potentially peculiar transport properties. In conventional quantum materials or cold atom systems alike, such exotic phases necessarily require non-local hopping and are therefore intrinsically unrealistic. In this work, we show how this hurdle can be surmounted through an experimentally feasible periodic driving scheme. In particular, by tuning the period of a two-step periodic driving or some experimentally accessible parameters, we show how to generate arbitrarily many nodal loops that are linked with various levels of complexity. Furthermore, we propose to use both the Berry phase winding and the Alexander polynomial topological invariant to characterize the fascinating linkages among the nodal loops. This work thus presents a class of exotic Floquet topological phase that has hitherto not been proposed in any realistic setup.