Chiral Majorana edge modes in anomalous Hall superconductor hybrids
In plain words
A quantum anomalous Hall film (a magnetic film with a quantized Hall current at zero field) covered by a superconductor was predicted to carry one-directional Majorana edge channels; a 2017 report of their signature was retracted, and they remain unobserved.
Precise statement
A magnetic topological insulator film in its quantum anomalous Hall state (Chern number $C = 1$) proximitized by an s-wave superconductor is predicted to enter a topological superconducting phase with Bogoliubov Chern number $N = 1$ and one chiral Majorana edge mode. The 2017 report of the predicted half-quantized two-terminal conductance $0.5 e^{2}/h$ was retracted, and Kayyalha et al. (Science 367, 2020, doi:10.1126/science.aax6361) showed such plateaus arise when the superconductor shorts the device. Determine whether the $N = 1$ phase exists in any such hybrid. An answer is a direct signature, such as thermal Hall conductance $\kappa_{xy} = \kappa_{0}/2$ with $\kappa_{0} = \pi^{2} k_{B}^{2} T/(3h)$, or an interferometric signal of a single chiral Majorana mode.
What would settle it
Thermal conductance or Majorana interferometry on a proximitized quantum anomalous Hall edge, with geometries that exclude superconducting shorts.
Status in the literature
Unverified note
No chiral Majorana edge mode is established as of 2026, to this survey's knowledge.