Magnetoelectrically tunable Andreev bound state spectra and spin polarization in p-wave Josephson junctions

Maria Teresa Mercaldo, Panagiotis Kotetes, and Mario Cuoco
Phys. Rev. B 100, 104519 – Published 19 September 2019

Abstract

We demonstrate how the boundary-driven reconstruction of the superconducting order parameter can be employed to manipulate the zero-energy Majorana bound states (MBSs) occurring in a topological Josephson junction. We focus on an interface of two p-wave superconductors, which are described by a spin-vector order parameter d. Apart from the sensitivity of d to external Zeeman/exchange fields, here, we show that the orientation of d throughout the junction can be controlled by electrically gating the weak link. The remarkable local character of this knob is a manifestation of the edge reconstruction of the order parameter, which takes place whenever different d-vector configurations in each superconductor compete and are close in energy. As a consequence, the spin-dependent superconducting-phase difference across the junction is switchable from 0 to π. Moreover, in the regime where multiple edge MBSs occur for each superconductor, the Andreev bound state (ABS) spectra can be twisted by the application of either a charge- or spin-phase difference across the interface and give rise to a rich diversity of nonstandard ABS dispersions. Interestingly, some of these dispersions show band crossings protected by fermion parity, despite their 2π-periodic character. These crossings additionally unlock the possibility of nontrivial topology in synthetic spaces, when considering networks of such 1D junctions. Lastly, the interface MBSs induce a distinct electronic spin polarization near the junction, which possesses a characteristic spatial pattern that allows the detection of MBSs using spin-polarized scanning tunneling microscopy. These findings unveil novel paths to mechanisms for ABS engineering and single-out signatures relevant for the experimental detection and manipulation of MBSs.

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  • Received 12 January 2019
  • Revised 10 August 2019

DOI:https://doi.org/10.1103/PhysRevB.100.104519

©2019 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Maria Teresa Mercaldo1, Panagiotis Kotetes2,3, and Mario Cuoco4,1

  • 1Dipartimento di Fisica “E. R. Caianiello,” Università di Salerno, IT-84084 Fisciano (SA), Italy
  • 2Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
  • 3CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
  • 4CNR-SPIN, IT-84084 Fisciano (SA), Italy

See Also

Synthetic Weyl Points and Chiral Anomaly in Majorana Devices with Nonstandard Andreev-Bound-State Spectra

Panagiotis Kotetes, Maria Teresa Mercaldo, and Mario Cuoco
Phys. Rev. Lett. 123, 126802 (2019)

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Vol. 100, Iss. 10 — 1 September 2019

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