Finite-size effects of transport behavior in MnBi2Te4 thin films

Mesoscopic structures bridge macro- and micro-systems, classical and quantum effects, providing valuable insights into fundamental physics and integrated semiconductor applications by virtue of their comparable dimensions to certain characteristic length scales. However, the systematic study of mesoscopic transport in MnBi2Te4 thin flake samples, the most promising candidate for realizing the high-temperature quantum anomalous Hall effect, presents considerable challenges due to their sample-specific properties, leaving some puzzles and not well-understood quantum phenomena. By employing non-destructive fabrication techniques, we have achieved full quantization in molecular beam epitaxy (MBE)-grown MnBi2Te4 thin films under high magnetic fields. The transport behaviors of uniform MBE-grown thin films at submicron and micron scales exhibit finite-size effects in both antiferromagnetic and magnetic configurations. The results reveal the relevant characteristic length scales within the system, offering a view to better understand the material's properties. Our work highlights the notable involvement of bulk electrons in quantized transport systems and sheds light on the scalable and intricate design of quantum device arrays based on the quantum anomalous Hall effect.