Imaging the Magnetically Driven Reconstruction of the Electronic States in the Antiferromagnetic Topological Insulator EuSn$_2$As$_2$
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arXiv
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| Auteurs principaux: | , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866911734978052096 |
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| author | Khizanishvili, Luka Jmukhadze, Erekle Raisa, Anika Sar, Divyanshi Gong, Mingda Romanova, Tetiana Kaczorowski, Dariusz Lee, Wei-Cheng Aynajian, Pegor |
| author_facet | Khizanishvili, Luka Jmukhadze, Erekle Raisa, Anika Sar, Divyanshi Gong, Mingda Romanova, Tetiana Kaczorowski, Dariusz Lee, Wei-Cheng Aynajian, Pegor |
| contents | The realization of the axion insulator phase in magnetic topological insulators is often hindered by crystalline symmetries that protect gapless surface states, even when time-reversal symmetry is broken. Here, we use variable-temperature scanning tunneling microscopy (STM) and spectroscopy (STS), complemented with density functional theory (DFT), to investigate the local electronic structure of the antiferromagnetic (AFM) topological insulator EuSn$_2$As$_2$ across its Néel transition at $T_N = 24$ K. On the (001) surface, we observe a substantial density of intrinsic Sn vacancies that introduce nanoscale electronic inhomogeneity and p-type doping. Upon cooling below $T_N$, we resolve the emergence of two distinct magnetically driven gaps: a $\sim$100 meV gap near the Fermi level and a $\sim$50 meV gap at the ARPES-resolved Dirac point. We attribute the former gap to AFM Brillouin-zone folding and hybridization. The characteristics of the 50 meV gap point toward the lifting of mirror-symmetry protection by Sn vacancies and the consequent mass gapping of the Dirac point, although contributions from AFM-induced folding hybridization cannot be entirely ruled out. Our findings provide real-space evidence for strong coupling between localized moments and itinerant topological states, highlighting exfoliable EuSn$_2$As$_2$ as a potential candidate for realizing axion-insulator-based devices. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2606_00337 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Imaging the Magnetically Driven Reconstruction of the Electronic States in the Antiferromagnetic Topological Insulator EuSn$_2$As$_2$ Khizanishvili, Luka Jmukhadze, Erekle Raisa, Anika Sar, Divyanshi Gong, Mingda Romanova, Tetiana Kaczorowski, Dariusz Lee, Wei-Cheng Aynajian, Pegor Strongly Correlated Electrons The realization of the axion insulator phase in magnetic topological insulators is often hindered by crystalline symmetries that protect gapless surface states, even when time-reversal symmetry is broken. Here, we use variable-temperature scanning tunneling microscopy (STM) and spectroscopy (STS), complemented with density functional theory (DFT), to investigate the local electronic structure of the antiferromagnetic (AFM) topological insulator EuSn$_2$As$_2$ across its Néel transition at $T_N = 24$ K. On the (001) surface, we observe a substantial density of intrinsic Sn vacancies that introduce nanoscale electronic inhomogeneity and p-type doping. Upon cooling below $T_N$, we resolve the emergence of two distinct magnetically driven gaps: a $\sim$100 meV gap near the Fermi level and a $\sim$50 meV gap at the ARPES-resolved Dirac point. We attribute the former gap to AFM Brillouin-zone folding and hybridization. The characteristics of the 50 meV gap point toward the lifting of mirror-symmetry protection by Sn vacancies and the consequent mass gapping of the Dirac point, although contributions from AFM-induced folding hybridization cannot be entirely ruled out. Our findings provide real-space evidence for strong coupling between localized moments and itinerant topological states, highlighting exfoliable EuSn$_2$As$_2$ as a potential candidate for realizing axion-insulator-based devices. |
| title | Imaging the Magnetically Driven Reconstruction of the Electronic States in the Antiferromagnetic Topological Insulator EuSn$_2$As$_2$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2606.00337 |