We have studied magnetotransport in arrays of niobium filled grooves in an $\mathrm{InAs}/{\mathrm{Al}}_x{\mathrm{Ga}}_{1-x}\mathrm{Sb}$ heterostructure. The critical field of up to 2.6 T permits one to enter the quantum Hall regime. In the superconducting state, we observe strong magnetoresistance oscillations, whose amplitude exceeds the Shubnikov–de Haas oscillations by a factor of about 2, when normalized to the background. Additionally, we find that above a geometry-dependent magnetic field value the sample in the superconducting state has a higher longitudinal resistance than in the normal state. Both observations can be explained with edge channels populated with electrons and Andreev-reflected holes.

• Received 7 April 2004

DOI:https://doi.org/10.1103/PhysRevLett.95.107001