Parity-Anomaly Quantum Anomalous Hall State in Mechanically Assembled Topological Insulator/Magnet Heterostructures

The family of quantized anomalous Hall effects provides remarkable electronic properties-for example, current flow perpendicular to the voltage and, in some cases, dissipationless edge states even with zero applied magnetic field, B-but their development is limited by their realization only at very low temperatures. The state of the art in magnetically-doped topological insulators (TIs) currently allows quantized Hall conductivities to persist up to temperatures of several Kelvin. An alternative approach, proximity-coupled TI/magnet heterostructures made using a chemically separate magnet, has up until now been more limited, with Hall quantization either completely absent or present only below 100 mK at B = 0. Here, we demonstrate one in the family of quantized anomalous Hall effects, the parity anomaly state (with Hall conductivity e²/2h) at temperatures up to 10 K in TI/magnet bilayers made by mechanical assembly of van der Waals layers. This represents an enhancement by a factor of 100 compared to previous proximity-coupled heterostructures grown by deposition.