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| Autores principales: | , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2026
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| Materias: | |
| Acceso en línea: | https://arxiv.org/abs/2601.18317 |
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| _version_ | 1866917223625392128 |
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| author | Liang, Bo Liu, Yichen Pang, Jie Deng, Hanbin Miao, Taimin Zhu, Wenpei Cai, Neng Zhang, Tiantian Liu, Jiayu Jiang, Zhicheng Liu, Zhanfeng Zhu, Hongen Li, Yuliang Li, Tongrui Xu, Mingkai Chen, Hao Ren, Xiaolin Yin, Chaohui Shu, Yingjie Chen, Yiwen Zhang, Yu-Tian Liu, Zhengtai Shen, Dawei Ye, Mao Zhang, Fengfeng Zhang, Shenjin Cui, Shengtao Sun, Zhe Miyamoto, Koji Okuda, Taichi Shimada, Kenya Yang, Lihong Yin, Jia-Xin Zhao, Lin Xu, Zuyan Zhang, Haijun Shi, Youguo Zhou, X. J. Liu, Guodong |
| author_facet | Liang, Bo Liu, Yichen Pang, Jie Deng, Hanbin Miao, Taimin Zhu, Wenpei Cai, Neng Zhang, Tiantian Liu, Jiayu Jiang, Zhicheng Liu, Zhanfeng Zhu, Hongen Li, Yuliang Li, Tongrui Xu, Mingkai Chen, Hao Ren, Xiaolin Yin, Chaohui Shu, Yingjie Chen, Yiwen Zhang, Yu-Tian Liu, Zhengtai Shen, Dawei Ye, Mao Zhang, Fengfeng Zhang, Shenjin Cui, Shengtao Sun, Zhe Miyamoto, Koji Okuda, Taichi Shimada, Kenya Yang, Lihong Yin, Jia-Xin Zhao, Lin Xu, Zuyan Zhang, Haijun Shi, Youguo Zhou, X. J. Liu, Guodong |
| contents | Kagome materials are at the frontier of condensed matter physics. An ideal kagome lattice features only one geometrically frustrated flat band spanning the entire momentum space and a single Dirac cone at the Brillouin-zone corners. However, for the first time, here we observe unusual flat-band and Dirac physics in the newly discovered "322" kagome material Ni3In2S2 by combining high-resolution synchrotron- and laser-based angle-resolved photoemission spectroscopy with a micro-focused beam, scanning tunneling microscopy, and first-principles calculations. We resolve two distinct electronic flat-band states located in close proximity to the Fermi level: a robust Topological Surface Flat Band at ~40 meV below the Fermi level on the Sulfur-terminated surface, originating from weak topological insulator states, and a kagome lattice-derived flat band at ~100 meV binding energy with an ultranarrow bandwidth (~5 meV). Instead of the single Dirac cone, the Indium-terminated surface hosts a rare two-dimensional Dirac-node arc state, where the gapless Dirac nodes extend along an open one-dimensional line crossing the Brillouin-zone boundary, exhibiting sharp linear dispersion, exceptionally high Fermi velocity, and pronounced circular dichroism. These findings establish Ni3In2S2 as a unique topological kagome metal in which multiple flat-band states of different physical origin coexist with an unusual Dirac-node arc, opening an avenue for discovering flat-band--driven and topology-enabled quantum phenomena. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_18317 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Unusual Dual Flat Bands and two-dimensional Dirac-node Arc State in Kagome Metal Ni3In2S2 Liang, Bo Liu, Yichen Pang, Jie Deng, Hanbin Miao, Taimin Zhu, Wenpei Cai, Neng Zhang, Tiantian Liu, Jiayu Jiang, Zhicheng Liu, Zhanfeng Zhu, Hongen Li, Yuliang Li, Tongrui Xu, Mingkai Chen, Hao Ren, Xiaolin Yin, Chaohui Shu, Yingjie Chen, Yiwen Zhang, Yu-Tian Liu, Zhengtai Shen, Dawei Ye, Mao Zhang, Fengfeng Zhang, Shenjin Cui, Shengtao Sun, Zhe Miyamoto, Koji Okuda, Taichi Shimada, Kenya Yang, Lihong Yin, Jia-Xin Zhao, Lin Xu, Zuyan Zhang, Haijun Shi, Youguo Zhou, X. J. Liu, Guodong Materials Science Kagome materials are at the frontier of condensed matter physics. An ideal kagome lattice features only one geometrically frustrated flat band spanning the entire momentum space and a single Dirac cone at the Brillouin-zone corners. However, for the first time, here we observe unusual flat-band and Dirac physics in the newly discovered "322" kagome material Ni3In2S2 by combining high-resolution synchrotron- and laser-based angle-resolved photoemission spectroscopy with a micro-focused beam, scanning tunneling microscopy, and first-principles calculations. We resolve two distinct electronic flat-band states located in close proximity to the Fermi level: a robust Topological Surface Flat Band at ~40 meV below the Fermi level on the Sulfur-terminated surface, originating from weak topological insulator states, and a kagome lattice-derived flat band at ~100 meV binding energy with an ultranarrow bandwidth (~5 meV). Instead of the single Dirac cone, the Indium-terminated surface hosts a rare two-dimensional Dirac-node arc state, where the gapless Dirac nodes extend along an open one-dimensional line crossing the Brillouin-zone boundary, exhibiting sharp linear dispersion, exceptionally high Fermi velocity, and pronounced circular dichroism. These findings establish Ni3In2S2 as a unique topological kagome metal in which multiple flat-band states of different physical origin coexist with an unusual Dirac-node arc, opening an avenue for discovering flat-band--driven and topology-enabled quantum phenomena. |
| title | Unusual Dual Flat Bands and two-dimensional Dirac-node Arc State in Kagome Metal Ni3In2S2 |
| topic | Materials Science |
| url | https://arxiv.org/abs/2601.18317 |