Two-dimensional topological superconductivity in Pb/Co/Si(111).

Ménard, Gerbold C; Guissart, Sébastien; Brun, Christophe; Leriche, Raphaël T; Trif, Mircea; Debontridder, François; Demaille, Dominique; Roditchev, Dimitri et al. · Nat Commun · 2017

basic_science · Level V

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Abstract

Just like insulators can present topological phases characterized by Dirac edge states, superconductors can exhibit topological phases characterized by Majorana edge states. In particular, one-dimensional topological superconductors are predicted to host zero-energy Majorana fermions at their extremities. By contrast, two-dimensional superconductors have a one-dimensional boundary which would naturally lead to propagating Majorana edge states characterized by a Dirac-like dispersion. In this paper we present evidences of one-dimensional dispersive in-gap edge states surrounding a two-dimensional topological superconducting domain consisting of a monolayer of Pb covering magnetic Co-Si islands grown on Si(111). We interpret the measured dispersive in-gap states as a spatial topological transition with a gap closure. Our method could in principle be generalized to a large variety of heterostructures combining a Rashba superconductor with a magnetic layer in order to be used as a platform for engineering topological quantum phases.