Andreev reflection at high magnetic fields: Evidence for electron and   hole transport in edge states
  We have studied magnetotransport in arrays of niobium filled grooves in an InAs/AlGaSb heterostructure. The critical field of up to 2.6 T permits 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 two, 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. 
J. Eroms, D. Weiss, J. De Boeck, G. Borghs, U. Z\"ulicke