Interplay Between Electronic Dephasing and Localization in Finite-Sized Chern Insulator

Anderson localization is anticipated to play a pivotal role in themanifestation of the quantum anomalous Hall effect, akin to its role inconventional quantum Hall effects. The significance of Anderson localization isparticularly pronounced in elucidating the reasons behind the fragility of theobserved quantum anomalous Hall state in the intrinsic magnetic topologicalinsulator MnBi2Te4 with a large predicted magnetic gap. Here, employing varyingsized MnBi2Te4 micro/nano-structures fabricated from a singlemolecular-beam-epitaxy-grown thin film, we have carried out a systematic size-and temperature-dependent study on the transport properties of the filmsregarding the quantum anomalous Hall states. The low-temperature transportproperties of the finite-sized MnBi2Te4 samples can be quantitativelyunderstood through Anderson localization, which plays an indispensable role instabilizing the ground states. At higher temperatures, the failure of electronlocalization induced by an excessively short electronic dephasing length isidentified as the cause of deviation from quantization. The work reveals thatelectronic dephasing and localization are non-negligible factors in designinghigh-temperature quantum anomalous Hall systems.