Topological phase transition and surface states in a non-Abelian charged nodal line photonic crystal

Park, Haedong, Jones, Alexander, Kim, Minkyung and Oh, Sang Soon ORCID: https://orcid.org/0000-0003-3093-7016 2024. Topological phase transition and surface states in a non-Abelian charged nodal line photonic crystal. Nanophotonics 13 (7) , pp. 1079-1089. 10.1515/nanoph-2023-0906

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Abstract

Topological charges of nodal lines in a multigap system are represented by non-Abelian numbers, and the Euler class, a topological invariant, can be used to explain their topological phase transitions, such as pair-annihilation of nodal lines. Up until now, no discussion of phase transitions of nodal lines in photonic crystals using the Euler class has been reported, despite the fact that the Euler class and topological phase transition have recently been addressed in metallic or acoustic crystals. Here, we show how the deformation of a photonic crystal causes topological phase transitions in the nodal lines, and the Euler class can be used to theoretically predict the nodal lines’ stability based on the non-Abelian topological charge theory. Specifically, by manipulating the separation between the two single diamond structures and the extent of structural distortion, we numerically demonstrate the topological transition of nodal lines, e.g., from nodal lines to nodal rings. We then demonstrate that the range of surface states is strongly influenced by the topological phase transition of nodal lines. Moreover, the Zak phase was used to explain the surface states’ existence.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Subjects:	Q Science > Q Science (General) Q Science > QC Physics
Publisher:	De Gruyter
ISSN:	2192-8606
Funders:	European Regional Development Fund
Date of First Compliant Deposit:	29 February 2024
Date of Acceptance:	10 February 2024
Last Modified:	04 Apr 2024 09:20
URI:	https://orca.cardiff.ac.uk/id/eprint/166712

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