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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2604.20399 |
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| _version_ | 1866913056278183936 |
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| author | Zou, Xiaorong Shin, Hyeon Suk Kang, Chang-Jong Huang, Baibiao Zang, Yanmei Dai, Ying Niu, Chengwang Myung, Chang Woo |
| author_facet | Zou, Xiaorong Shin, Hyeon Suk Kang, Chang-Jong Huang, Baibiao Zang, Yanmei Dai, Ying Niu, Chengwang Myung, Chang Woo |
| contents | The discovery of higher-order topological insulator (HOTI) has established a new paradigm for understanding symmetry-constrained boundary electronic states. Here, based on first-principles calculations, we demonstrate the emergence of HOTI phase in organic lattices of two-dimensional azulenoid-kekulene-type carbon allotropes, namely AKC-[3,3] and AKC-[6,0]. Enabled by the $C_6$ rotational symmetry, the nontrivial bulk topology is confirmed through the topological invariant and fractionally quantized corner charge, giving $\{[M^{(I)}_{2}],[K^{(3)}_{2}]\}$ = $\{0,2\}$ and $Q_{\mathrm{corner}} = e/3$, respectively, accompanied by the emergence of exotic corner states in nanoflakes. Notably, the structural modifications are explored, revealing that in the derived structure PAK-[6,0], whose corner-localized states are preserved, highlighting the robustness of the higher-order topological phase. These findings highlight azulenoid-kekulene-based carbon allotropes as a promising platform to explore the interplay between structural design, crystalline symmetry, and higher-order topological boundary responses in two dimensional carbon systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_20399 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Second-order topology in two-dimensional azulenoid kekulene carbon lattices Zou, Xiaorong Shin, Hyeon Suk Kang, Chang-Jong Huang, Baibiao Zang, Yanmei Dai, Ying Niu, Chengwang Myung, Chang Woo Materials Science Computational Physics The discovery of higher-order topological insulator (HOTI) has established a new paradigm for understanding symmetry-constrained boundary electronic states. Here, based on first-principles calculations, we demonstrate the emergence of HOTI phase in organic lattices of two-dimensional azulenoid-kekulene-type carbon allotropes, namely AKC-[3,3] and AKC-[6,0]. Enabled by the $C_6$ rotational symmetry, the nontrivial bulk topology is confirmed through the topological invariant and fractionally quantized corner charge, giving $\{[M^{(I)}_{2}],[K^{(3)}_{2}]\}$ = $\{0,2\}$ and $Q_{\mathrm{corner}} = e/3$, respectively, accompanied by the emergence of exotic corner states in nanoflakes. Notably, the structural modifications are explored, revealing that in the derived structure PAK-[6,0], whose corner-localized states are preserved, highlighting the robustness of the higher-order topological phase. These findings highlight azulenoid-kekulene-based carbon allotropes as a promising platform to explore the interplay between structural design, crystalline symmetry, and higher-order topological boundary responses in two dimensional carbon systems. |
| title | Second-order topology in two-dimensional azulenoid kekulene carbon lattices |
| topic | Materials Science Computational Physics |
| url | https://arxiv.org/abs/2604.20399 |