Electrostatic gating and the interference of chiral Majoranas in thin slabs of magnetic topological insulators

Abstract

We study the interference of chiral Majoranas in a magnetic topological insulator thin slab having a grounded section proximity coupled to a superconductor and another section under the influence of top-bottom electrostatic gating. The gated section locally widens an energy gap and mediates the coupling between the quantum anomalous Hall states of the leads and the chiral Majorana states of the proximitized sector. Local and non-local conductances offer measurable hints of the existence of transport mediated by chiral Majorana modes. Local conductances on the two leads reveal characteristic oscillatory patterns as a function of the gating strength, with peculiar correlations depending on the distance between gated and proximitized sectors. A gate tunable Majorana diode effect on nonlocal conductances emerges when the chemical potential deviates from zero. We suggest a protocol to identify chiral Majorana physics based on a sequence of electrostatic gates that allows the tuning of chiral Majorana interference.

11 pages, 8 figures

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