Topological properties of chains of magnetic impurities on a superconducting substrate: Interplay between the Shiba band and ferromagnetic wire limits

Gian Marcello Andolina and Pascal Simon
Phys. Rev. B 96, 235411 – Published 11 December 2017

Abstract

We consider a one-dimensional system combining local magnetic moments and a delocalized metallic band on top of a superconducting substrate. This system can describe a chain of magnetic impurities with both localized polarized orbitals and delocalized s-like orbitals or a conducting wire with embedded magnetic impurities. We study the interplay between the one-dimensional Shiba band physics arising from the interplay between magnetic moments and the substrate and the delocalized wire-like conduction band on top of the superconductor. We derive an effective low-energy Hamiltonian in terms of two coupled asymmetric Kitaev-like Hamiltonians and analyze its topological properties. We have found that this system can host multiple Majorana bound states at its extremities provided a magnetic mirror symmetry is present. We compute the phase diagram of the system depending on the magnetic exchange interactions, the impurity distance, and especially the coupling between both bands. In the presence of inhomogeneities which typically break this magnetic mirror symmetry, we show that the coexistence of a Shiba and wire delocalized topological band can drive the system into a nontopological regime with a splitting of Majorana bound states.

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  • Received 14 September 2017

DOI:https://doi.org/10.1103/PhysRevB.96.235411

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Gian Marcello Andolina1,2,3,* and Pascal Simon1

  • 1Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris Saclay, 91405 Orsay Cedex, France
  • 2NEST, Scuola Normale Superiore, I-56126 Pisa, Italy
  • 3Istituto Italiano di Tecnologia, Graphene Labs, Via Morego 30, I-16163 Genova, Italy

  • *gian.andolina@sns.it

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Issue

Vol. 96, Iss. 23 — 15 December 2017

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