Majorana edge and zero modes at topological insulator/superconductor heterojunctions in the quantum Hall regime.

One promising proposal to realize Majorana quasiparticles relies on the electronic structure of topological insulator (TI) surface states that are proximity coupled to an $s$-wave superconductor, as described in the Fu-Kane model, combined with broken time-reversal symmetry.
However, the coupling between the two surfaces of TI thin films and the corresponding Hilbert space doubling can lead to trivial superconducting states unless time-reversal symmetry is strongly broken. In this work we study a realistic TI thin film/s-wave superconductor heterojunction model with time-reversal broken by an external magnetic field that drives the system toward quantum Hall states containing vortex lattices inherited from the parent s-wave superconductor. We will discuss practical strategies for engineering isolated Majorana zero modes, and chiral Majorana edge modes in such a system.