Higher-order Dirac semimetal in a photonic crystal
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 topo...
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المؤلفون الرئيسيون: | , , , , , |
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مؤلفون آخرون: | |
التنسيق: | مقال |
اللغة: | English |
منشور في: |
2022
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الموضوعات: | |
الوصول للمادة أونلاين: | https://hdl.handle.net/10356/156871 |
الوسوم: |
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المؤسسة: | Nanyang Technological University |
اللغة: | English |
الملخص: | 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. |
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