ArXiv · 2025
Yuanze Li (State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, People's Republic of China), Jiahao Chen (State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, People's Republic of China), Renfei Wang (International Center for Quantum Materials, Peking University, Beijing, People's Republic of China), Yifan Zhang (School of Information Science and Technology, ShanghaiTech University, Shanghai, People's Republic of China), Yingdong Deng (School of Physical Science and Technology, ShanghaiTech University, Shanghai, People's Republic of China), Jin Xie (School of Physical Science and Technology, ShanghaiTech University, Shanghai, People's Republic of China), Xufeng Kou (School of Information Science and Technology, ShanghaiTech University, Shanghai, People's Republic of China, ShanghaiTech Laboratory for Topological Physics, School of Physical Science and Technology, ShanghaiTech University, Shanghai, People's Republic of China), Yang Liu (International Center for Quantum Materials, Peking University, Beijing, People's Republic of China), Tian Liang (State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, People's Republic of China, Frontier Science Center for Quantum Information, Beijing, People's Republic of China)
The quantum anomalous Hall effect in magnetically doped topological insulators exhibits a quantized Hall conductance σ_xy = e²/h arising from the two-dimensional surface states. While conventional transport probes confirm this quantization, they remain insensitive to the field-induced surface charge accumulation as a direct manifestation of σ_xy. Here, we experimentally validate an out-of-plane capacitive method that directly detects this quantized charge accumulation in a quantum anomalous Hall system. Using Corbino and simple disk devices, we measure charge accumulation proportional to field variation Δ B, with dissipation characterized by longitudinal conductance σₓₓ and frequency f. A quantitative dissipation model extracts the intrinsic quantized charge density η₀ = (e²/h)Δ B, which is confirmed through f- and σₓₓ-dependent measurements. Under ultra-low dissipation (σₓₓ ≈ 10⁻⁹ S), we directly resolve the fully quantized charge accumulation. This methodology establishes a direct charge-accumulation probe and provides a pathway toward detecting the topological magnetoelectric effect, a condensed matter manifestation of the four-dimensional quantum Hall effect.
