No abstract

We simulate a hybrid superconductor-graphene device in the quantum Hall regime to identify the origin of downstream resistance oscillations in a recent experiment [Zhao et al., Nature Physics 16, (2020)]. In addition to the previously studied Mach-Zehnder interference between the valley-polarized edge states, we consider disorder-induced scattering, and the appearance of the counter-propagating states generated by the interface density mismatch. Comparing our results with the experiment, we conclude that the observed oscillations are induced by the interfacial disorder, and that lattice-matched superconductors are necessary to observe the alternative ballistic effects.

We perform realistic simulations of a hybrid superconductor-graphene device in the quantum Hall regime to indentify the origin of downstream resistance oscillations in a recent experiment [Zhao et. al. Nature Physics 16, (2020)]. A comparison between the simulations and the experimental data suggests that disorderinduced intervalley scattering at the normal-superconductor (NS) interface can be the dominant cause of oscillations. We also show conductance oscillations due to additional edge states on clean interfaces with Fermi level mismatch. However, the regular pattern as a function of external parameters is not visible in the presence of disorder. Our work provides a way to qualitatively probe the quality of NS interfaces on multiterminal quantum Hall devices.