近日，美国康奈尔大学Katja C. Nowack团队实现了可视化量子反常霍尔效应的分解。相关论文于2026年3月10日发表在《美国科学院院刊》杂志上。

从电子系统、力学系统、冷原子系统到光子平台，拓扑非平庸物质的研究正在飞速发展，然而理解拓扑保护的失效机制仍是一项重大挑战。

研究组通过结合磁成像与全局电输运测量，直观呈现了磁性掺杂拓扑绝缘体中量子反常霍尔效应的电流诱导击穿过程。研究发现耗散出现在电接触附近的局域热点区域，该处霍尔角的突变导致电流密度发生显著畸变。通过将局域磁化强度变化作为电子温度的替代指标，研究组直接观测到在击穿区域，热点处乃至整个器件中的电子被驱动至与晶格非平衡的状态。

通过表征器件中的能量弛豫过程，研究组揭示了量子化击穿完全由电子加热主导，且毫开尔文温度下热弛豫强度的衰减限制了量子反常霍尔效应的鲁棒性。研究组为诊断拓扑材料中的能量弛豫提供了理论框架，并将指导在磁性拓扑绝缘体中实现稳定的拓扑保护。

附：英文原文

Title: Visualizing the breakdown of the quantum anomalous Hall effect

Author: Ferguson, G. M, Xiao, Run, Richardella, Anthony R., Kaczmarek, Austin, Samarth, Nitin, Nowack, Katja C.

Issue&Volume: 2026-3-10

Abstract: of topologically nontrivial 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 changes in 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.

DOI: 10.1073/pnas.2515400123

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2515400123