Effects of domain walls in quantum anomalous Hall insulator/superconductor heterostructures
AbstractIn a recent experiment, half-quantized longitudinal conductance plateaus (HQCPs) of height e22h have been observed in quantum anomalous Hall (QAH) insulator/superconductor heterostructure transport measurements. However, there are debates about whether these HQCPs are caused by Majorana edge modes or other trivial reasons. It was predicted that HQCPs can only appear when the Hall conductance σxy is quantized. Surprisingly, HQCPs appear when the Hall conductance σxy is only 80% of the quantized value at which extra conducting channels in the bulk should ruin the HQCPs. In this Rapid Communication, we explain how domain walls can cause σxy to deviate from its quantized value and at the same time maintain the quantization of HQCPs. Importantly, our study also explains a long standing puzzle of why ρxx can be finite when ρxy is quantized in QAH systems.