The chiral Majorana fermion is a massless self-conjugate fermionic particle that could arise as the quasiparticle edge state of a two-dimensonal topological state of matter. Here we propose a new platform for a chiral topological superconductor (TSC) in two dimensions with multiple $N$ chiral Majorana fermions from a quantized anomalous Hall insulator in proximity to an $s$-wave superconductor with nontrivial band topology. A concrete example is that a $N=3$ chiral TSC is realized by coupling a magnetic topological insulator to the ion-based superconductor such as ${\mathrm{FeTe}}_{0.55}{\mathrm{Se}}_{0.45}$. We further propose the electrical and thermal transport experiments to detect the Majorana nature of three chiral edge fermions. A smoking gun signature is that the two-terminal electrical conductance of a quantized anomalous Hall-TSC junction obeys a unique distribution averaged to $(2/3)e^2/h$, which is due to the random edge mode mixing of chiral Majorana fermions and is distinguished from possible trivial explanations. The homogenous system proposed here provides an ideal platform for studying the exotic physics of chiral Majorana fermions.

• Received 18 June 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.256801