Supercurrent as a Probe for Topological Superconductivity in Magnetic Adatom Chains

Abstract

A magnetic adatom chain, proximity coupled to a conventional superconductor with spin-orbit coupling, exhibits locally an odd-parity, spin-triplet pairing amplitude. We show that the singlet-triplet junction, thus formed, leads to a net spin accumulation in the near vicinity of the chain. The accumulated spins are polarized along the direction of the local $\mathbf{d}$-vector for triplet pairing and generate an enhanced persistent current flowing around the chain. The spin polarization and the "supercurrent" reverse their directions beyond a critical exchange coupling strength at which the singlet superconducting order changes its sign on the chain. The current is strongly enhanced in the topological superconducting regime where Majorana bound states appear at the chain ends. The current and the spin profile offer alternative routes to characterize the topological superconducting state in adatom chains and islands.

5 pages, 3 figures, 5 pages of supplemental materials

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• Majorana corner states on the dice lattice
• Delocalisation of Majorana quasiparticles in plaquette--nanowire hybrid system
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• Shiba states in systems with density of states singularities
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• Magnetic flux induced topological superconductivity in magnetic atomic rings
• Bound states induced by the ferromagnetic dimer in a triangular lattice