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Portrait of Martin Leijnse; Photo: Kennet Ruona

Martin Leijnse

Professor, Member of NanoLund Management Group

Portrait of Martin Leijnse; Photo: Kennet Ruona

Topological superconductivity in semiconductor-superconductor-magnetic-insulator heterostructures

Author

  • A. Maiani
  • R. Seoane Souto
  • M. Leijnse
  • K. Flensberg

Summary, in English

Hybrid superconductor-semiconductor heterostructures are promising platforms for realizing topological superconductors and exploring Majorana bound state physics. Motivated by recent experimental progress, we theoretically study how magnetic insulators offer an alternative to the use of external magnetic fields for reaching the topological regime. We consider different setups, where (1) the magnetic insulator induces an exchange field in the superconductor, which leads to a splitting in the semiconductor by proximity effect, and (2) the magnetic insulator acts as a spin-filter tunnel barrier between the superconductor and the semiconductor. We show that the spin splitting in the superconductor alone cannot induce a topological transition in the semiconductor. To overcome this limitation, we propose to use a spin-filter barrier that enhances the magnetic exchange and provides a mechanism for a topological phase transition. Moreover, the spin-dependent tunneling introduces a strong dependence on the band alignment, which can be crucial in quantum-confined systems. This mechanism opens up a route towards networks of topological wires with fewer constraints on device geometry compared to previous devices that require external magnetic fields.

Department/s

  • Solid State Physics
  • NanoLund: Center for Nanoscience

Publishing year

2021

Language

English

Publication/Series

Physical Review B

Volume

103

Issue

10

Document type

Journal article

Publisher

American Physical Society

Topic

  • Condensed Matter Physics

Status

Published

ISBN/ISSN/Other

  • ISSN: 2469-9950