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Topological superconductivity in semiconductor-superconductor-magnetic-insulator heterostructures

Maiani, A. ; Seoane Souto, R. LU orcid ; Leijnse, M. LU and Flensberg, K. (2021) In Physical Review B 103(10).
Abstract

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... (More)

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.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Review B
volume
103
issue
10
article number
104508
publisher
American Physical Society
external identifiers
  • scopus:85102901592
ISSN
2469-9950
DOI
10.1103/PhysRevB.103.104508
language
English
LU publication?
yes
id
032a37c6-e82e-453a-98a8-b1ae6e65dd3e
date added to LUP
2021-03-31 08:49:37
date last changed
2023-11-08 11:58:42
@article{032a37c6-e82e-453a-98a8-b1ae6e65dd3e,
  abstract     = {{<p>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.</p>}},
  author       = {{Maiani, A. and Seoane Souto, R. and Leijnse, M. and Flensberg, K.}},
  issn         = {{2469-9950}},
  language     = {{eng}},
  number       = {{10}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review B}},
  title        = {{Topological superconductivity in semiconductor-superconductor-magnetic-insulator heterostructures}},
  url          = {{http://dx.doi.org/10.1103/PhysRevB.103.104508}},
  doi          = {{10.1103/PhysRevB.103.104508}},
  volume       = {{103}},
  year         = {{2021}},
}