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Title: Higher-order Dirac semimetal in a photonic crystal
Authors: Wang, Zihao
Liu, Dongjue
Teo, Hau Tian
Wang, Qiang
Xue, Haoran
Zhang, Baile
Keywords: Science::Physics::Optics and light
Issue Date: 2022
Source: Wang, Z., Liu, D., Teo, H. T., Wang, Q., Xue, H. & Zhang, B. (2022). Higher-order Dirac semimetal in a photonic crystal. Physical Review B, 105(6), L060101-.
Project: NRF-CRP23-2019-0007
Journal: Physical Review B 
Abstract: The recent discovery of higher-order topology has largely enriched the classification of topological materials. Theoretical and experimental studies have unveiled various higher-order topological insulators that exhibit topologically protected corner or hinge states. More recently, higher-order topology has been introduced to topological semimetals. Thus far, realistic models and experimental verifications on higher-order topological semimetals are still very limited. Here we design and demonstrate a three-dimensional photonic crystal that realizes a higher-order Dirac semimetal phase. Numerical results on the band structure show that the designed three-dimensional photonic crystal is able to host two fourfold Dirac points, which are connected in the momentum-space projections via higher-order hinge states localized at the hinge. The higher-order topology can be characterized by the topological invariant χ(6) at different values of k_z . An experiment at microwave frequencies is also presented to measure the hinge state dispersion. Our work demonstrates the physical realization of a higher-order Dirac semimetal phase and paves the way to explore higher-order topological semimetal phases in three-dimensional photonic systems.
ISSN: 2469-9950
DOI: 10.1103/PhysRevB.105.L060101
Rights: © 2022 American Physical Society. All rights reserved. This paper was published in Physical Review B and is made available with permission of American Physical Society.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:EEE Journal Articles
SPMS Journal Articles

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