The interplay between superconductivity, magnetic field, and spin-orbit coupling can lead to the realization of nontrivial topological phases. Recent experiments have found signatures of such phases in magnetic nanoflakes formed by nanostructures coupled to a superconducting substrate. These heterostructures comprise a topologically nontrivial region surrounded by a trivial one due to the finite magnetic exchange field induced by the magnetic nanoflake. The analysis of the topological phase diagram of such a system shows that a similar phase separation occurs by tuning the chemical potential of the nanoflake. In this paper, we study such a possibility in detail, analyzing the spatial extent of the edge modes circulating around the nanoflake and discussing some practical implementations. We also show how the chirality of Majorana edge states can be probed using scanning tunneling spectroscopy with a double-tip setup.

• Received 24 August 2020
• Revised 12 November 2020
• Accepted 12 November 2020

DOI:https://doi.org/10.1103/PhysRevB.102.245405