Andreev edge state in the quantum Hall regime*

We investigate Andreev reflections in the quantum Hall regime. We study an encapsulated graphene sample contacted by both superconducting and normal electrodes. In the well-quantized regime, we find evidence for Andreev reflections of the QH edge states traveling along the superconducting contacts. The observed spectroscopic features decay to zero with increasing temperature and magnetic field. We attribute them to beating between electron-hole modes hybridized by Andreev reflections. These chiral modes under certain conditions are predicted to be Majorana-Weyl fermions.