Scale-Invariant Quantum Anomalous Hall Effect in Magnetic Topological Insulators beyond the Two-Dimensional Limit

TLDR

The study investigates the quantum anomalous Hall effect and chiral transport in millimeter‑size Cr₀.₁₂Bi₀.₂₆Sb₀.₆₂Te₃ films, extending QAHE into the three‑dimensional thickness regime to explore its universality and new phases with tunable Chern numbers. High‑quality millimeter‑size films exhibit a robust quantized Hall conductance of e²/h that persists beyond the two‑dimensional hybridization limit, with non‑local transport confirming chiral edge conduction, while a weakly field‑dependent longitudinal resistance in 10‑QL samples indicates thickness‑dependent dissipative channels; the scale‑invariant, dissipationless chiral propagation observed on a macroscopic scale marks a significant step toward ideal low‑power interconnects.

Abstract

We investigate the quantum anomalous Hall Effect (QAHE) and related chiral transport in the millimeter-size (Cr0.12Bi0.26Sb0.62)2Te3 films. With high sample quality and robust magnetism at low temperatures, the quantized Hall conductance of e2/h is found to persist even when the film thickness is beyond the two-dimensional (2D) hybridization limit. Meanwhile, the Chern insulator-featured chiral edge conduction is manifested by the non-local transport measurements. In contrast to the 2D hybridized thin film, an additional weakly field-dependent longitudinal resistance is observed in the 10 quintuple-layer film, suggesting the influence of the film thickness on the dissipative edge channel in the QAHE regime. The extension of QAHE into the three-dimensional thickness region addresses the universality of this quantum transport phenomenon and motivates the exploration of new QAHE phases with tunable Chern numbers. In addition, the observation of the scale-invariant dissipationless chiral propagation on a macroscopic scale makes a major stride towards ideal low-power interconnect applications.