Evidence for Half-Quantized Chiral Edge Current in a C = 1/2 Parity Anomaly State
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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866918468631134208 |
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| author | Zhuo, Deyi Zhang, Bomin Zhou, Humian Tay, Han Liu, Xiaoda Xi, Zhiyuan Chen, Chui-Zhen Chang, Cui-Zu |
| author_facet | Zhuo, Deyi Zhang, Bomin Zhou, Humian Tay, Han Liu, Xiaoda Xi, Zhiyuan Chen, Chui-Zhen Chang, Cui-Zu |
| contents | A single massive Dirac surface band is predicted to exhibit a half-quantized Hall conductance, a hallmark of the C = 1/2 parity anomaly state in quantum field theory. Experimental signatures of the C = 1/2 parity anomaly state have been observed in semi-magnetic topological insulator (TI) bilayers, yet whether it supports a half-quantized chiral edge current remains elusive. Here, we observe a robust half-quantized Hall conductance plateau in a molecular beam epitaxy (MBE)-grown asymmetric magnetic TI trilayer under specific in-plane magnetic field regimes, corresponding to the C = 1/2 parity anomaly state. Within this state, both nonlocal and nonreciprocal transport signals are greatly enhanced, which we identify as direct evidence for a half-quantized chiral edge current localized at the boundary of the top gapped surface. Our numerical simulations demonstrate that this half-quantized chiral edge channel is the essential carrier of the observed half-quantized Hall conductance plateau, analogous to the quantized chiral edge channel in the C = 1 quantum anomalous Hall state. Our results provide experimental evidence for the half-quantized chiral edge transport in a C = 1/2 parity anomaly state. This work establishes asymmetric magnetic TI trilayers as a platform for probing single Dirac fermion physics and paves the way to explore a series of exciting phenomena in the C = 1/2 parity anomaly state, including the topological magnetoelectric effect and quantized magneto-optical response. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_15525 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Evidence for Half-Quantized Chiral Edge Current in a C = 1/2 Parity Anomaly State Zhuo, Deyi Zhang, Bomin Zhou, Humian Tay, Han Liu, Xiaoda Xi, Zhiyuan Chen, Chui-Zhen Chang, Cui-Zu Mesoscale and Nanoscale Physics Materials Science A single massive Dirac surface band is predicted to exhibit a half-quantized Hall conductance, a hallmark of the C = 1/2 parity anomaly state in quantum field theory. Experimental signatures of the C = 1/2 parity anomaly state have been observed in semi-magnetic topological insulator (TI) bilayers, yet whether it supports a half-quantized chiral edge current remains elusive. Here, we observe a robust half-quantized Hall conductance plateau in a molecular beam epitaxy (MBE)-grown asymmetric magnetic TI trilayer under specific in-plane magnetic field regimes, corresponding to the C = 1/2 parity anomaly state. Within this state, both nonlocal and nonreciprocal transport signals are greatly enhanced, which we identify as direct evidence for a half-quantized chiral edge current localized at the boundary of the top gapped surface. Our numerical simulations demonstrate that this half-quantized chiral edge channel is the essential carrier of the observed half-quantized Hall conductance plateau, analogous to the quantized chiral edge channel in the C = 1 quantum anomalous Hall state. Our results provide experimental evidence for the half-quantized chiral edge transport in a C = 1/2 parity anomaly state. This work establishes asymmetric magnetic TI trilayers as a platform for probing single Dirac fermion physics and paves the way to explore a series of exciting phenomena in the C = 1/2 parity anomaly state, including the topological magnetoelectric effect and quantized magneto-optical response. |
| title | Evidence for Half-Quantized Chiral Edge Current in a C = 1/2 Parity Anomaly State |
| topic | Mesoscale and Nanoscale Physics Materials Science |
| url | https://arxiv.org/abs/2509.15525 |