Symmorphic intersecting nodal rings in semiconducting layers

TL;DR

This paper identifies conditions for linked nodal rings in symmorphic crystals and proposes layered semiconducting structures as topological semimetals with tunable properties and unique surface states.

Contribution

It introduces a critical condition for linked nodal rings in symmorphic crystals and demonstrates their realization in layered semiconducting structures with tunable topological phases.

Findings

Linked nodal rings can exist in symmorphic crystals under specific conditions.

Stacked semiconducting layers can host topological linked nodal ring semimetals.

External strain can induce transitions between different linked nodal ring types.

Abstract

The unique properties of topological semimetals have strongly driven efforts to seek for new topological phases and related materials. Here, we identify a critical condition for the existence of linked nodal rings (LNRs) in symmorphic crystals, and propose that three types of LNRs, named as alpha-, beta- and gamma-type, can be obtained by stacking semiconducting layers. Several honeycomb structures are suggested to be topological LNR semimetals, including layered and "hidden" layered structures. Transitions between the three types of LNRs can be driven by external strains. Interesting surface states other than drumhead states are found in these topological materials.