Visualizing the breakdown of the quantum anomalous Hall effect
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arXiv
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| Auteurs principaux: | , , , , , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866912258089549824 |
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| author | Ferguson, George M. Xiao, Run Richardella, Anthony R. Kaczmarek, Austin Samarth, Nitin Nowack, Katja C. |
| author_facet | Ferguson, George M. Xiao, Run Richardella, Anthony R. Kaczmarek, Austin Samarth, Nitin Nowack, Katja C. |
| contents | The creation of topologically non-trivial matter across electronic, mechanical, cold-atom, and photonic platforms is advancing rapidly, yet understanding the breakdown of topological protection remains a major challenge. In this work, we use magnetic imaging combined with global electrical transport measurements to visualize the current-induced breakdown of the quantum anomalous Hall effect (QAHE) in a magnetically doped topological insulator. We find that dissipation emerges at localized hot spots near electrical contacts, where an abrupt change in Hall angle leads to significant distortions of the current density. Using the local magnetization as a proxy for electron temperature, we directly observe that the electrons are driven out of equilibrium with the lattice at the hot spots and throughout the device in the breakdown regime. By characterizing energy relaxation processes in our device, we show that the breakdown of quantization is governed entirely by electron heating, and that a vanishing thermal relaxation strength at millikelvin temperatures limits the robustness of the QAHE. Our findings provide a framework for diagnosing energy relaxation in topological materials and will guide realizing robust topological protection in magnetic topological insulators. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_02633 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Visualizing the breakdown of the quantum anomalous Hall effect Ferguson, George M. Xiao, Run Richardella, Anthony R. Kaczmarek, Austin Samarth, Nitin Nowack, Katja C. Mesoscale and Nanoscale Physics The creation of topologically non-trivial matter across electronic, mechanical, cold-atom, and photonic platforms is advancing rapidly, yet understanding the breakdown of topological protection remains a major challenge. In this work, we use magnetic imaging combined with global electrical transport measurements to visualize the current-induced breakdown of the quantum anomalous Hall effect (QAHE) in a magnetically doped topological insulator. We find that dissipation emerges at localized hot spots near electrical contacts, where an abrupt change in Hall angle leads to significant distortions of the current density. Using the local magnetization as a proxy for electron temperature, we directly observe that the electrons are driven out of equilibrium with the lattice at the hot spots and throughout the device in the breakdown regime. By characterizing energy relaxation processes in our device, we show that the breakdown of quantization is governed entirely by electron heating, and that a vanishing thermal relaxation strength at millikelvin temperatures limits the robustness of the QAHE. Our findings provide a framework for diagnosing energy relaxation in topological materials and will guide realizing robust topological protection in magnetic topological insulators. |
| title | Visualizing the breakdown of the quantum anomalous Hall effect |
| topic | Mesoscale and Nanoscale Physics |
| url | https://arxiv.org/abs/2503.02633 |