Disorder-induced half-integer quantized conductance plateau in quantum anomalous Hall insulator-superconductor structures

Abstract

Recent experiments [Science 357, 294 (2017)] have observed a half-quantized electrical conductance plateau, a proposed signature of chiral Majorana fermions. Such Majoranas have been argued to occur generically when a quantum anomalous Hall insulator is tuned to its plateau transition and proximitized by a superconductor. The authors show here that such half-quantized conductance can also occur in this system even in the absence of chiral Majorana fermions, once experimental disorder and temperature are considered. This work therefore motivates the search for more compelling evidence of chiral Majorana fermions in this system, such as quantum coherent interferometry or half-quantized thermal conductance.