Crossed Andreev reflection in spin-polarized chiral edge states due to the Meissner effect

We consider a hybrid quantum Hall-superconductor system, where a superconducting finger with oblique profile is wedged into a two-dimensional electron gas in the presence of a perpendicular magnetic field, as considered by Lee et al., Nat. Phys. 13, 693 (2017). The electron gas is in the quantum Hall regime at filling factor nu = 1. Due to the Meissner effect, the perpendicular magnetic field close to the quantum Hall-superconductor boundary is distorted and gives rise to an in-plane component of the magnetic field. This component enables nonlocal crossed Andreev reflection between the spin-polarized chiral edge states running on opposite sides of the superconducting finger, thus opening a gap in the spectrum of the edge states without the need of spin-orbit interaction or nontrivial magnetic textures. We compute numerically the transport properties of this setup and show that a negative resistance exists as a consequence of nonlocal Andreev processes. We also obtain numerically the zero-energy local density of states, which systematically shows peaks stable to disorder. The latter result is compatible with the emergence of Majorana bound states.

Automated summary

In this hybrid quantum Hall-superconductor system, nonlocal crossed Andreev reflection can occur due to the distortion effect of the Maxwell equations, resulting in a gap in the spectrum of the edge states. Numerical calculations also reveal the existence of negative resistance and stable zero-energy local density of states, which may be related to the emergence of Majorana bound states.