Optimizing proximitized magnetic topological insulator nanoribbons for Majorana bound states

[en] Heterostructures comprised of a magnetic topological insulator (MTI) placed in the proximity of an <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>s</a:mi></a:math>-wave superconductor have emerged as a platform for the practical realization of Majorana bound states (MBSs). More specifically, it has been theoretically predicted that MBS can appear in proximitized MTI nanoribbons (PNRs) in the quantum anomalous Hall regime. As with all MBS platforms, disorder and device imperfections can be detrimental to the formation of robust and well-separated MBSs that are suitable for fusion and braiding experiments. Here, we identify the optimal conditions for obtaining a topological superconducting gap that is against disorder, with spatially separated MBSs in PNRs, and introduce a figure of merit that encompasses these conditions. Particular attention is given to the thin-film limit of magnetic topological insulators (MTIs), where the hybridization of the surface states cannot be neglected, and to the role of electron-hole asymmetry in the low-energy physics of the system. Based on our numerical results, we find that (1) MTI thin films that are normal (rather than quantum spin Hall) insulators for zero magnetization are favorable, (2) strong electron-hole asymmetry causes the stability and robustness of MBS to be very different for chemical potentials above or below the Dirac point, and (3) the magnetization strength should preferably be comparable to the hybridization or confinement energy of the surface states, whichever is largest.

Disciplines :

Physics

Author, co-author :

ZSURKA, Eduard ; University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS) ; Forschungszentrum Jülich ; Jülich-Aachen Research Alliance

Di Miceli, Daniele ; University of Luxembourg ; Institute for Cross-Disciplinary Physics and Complex Systems (IFISC)

LEGENDRE, Julian ; University of Luxembourg > Faculty of Science, Technology and Medicine > Department of Physics and Materials Science > Team Thomas SCHMIDT

Serra, Llorenç ; Institute for Cross-Disciplinary Physics and Complex Systems (IFISC) ; University of the Balearic Islands

Grützmacher, Detlev ; Forschungszentrum Jülich ; Jülich-Aachen Research Alliance

Moors, Kristof ; Forschungszentrum Jülich ; Jülich-Aachen Research Alliance

SCHMIDT, Thomas ; University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Physics and Materials Science (DPHYMS)

External co-authors :

yes

Language :

English

Title :

Optimizing proximitized magnetic topological insulator nanoribbons for Majorana bound states

Publication date :

2025

Journal title :

Physical Review. B

ISSN :

2469-9950

eISSN :

2469-9969

Publisher :

American Physical Society (APS)

Volume :

112

Issue :

Peer reviewed :

Peer Reviewed verified by ORBi

Additional URL :

https://link.aps.org/article/10.1103/x737-p9mq

Funders :

Deutsche Forschungsgemeinschaft
NextGenerationEU
Bayerische Staatsministerium für Wirtschaft, Landesentwicklung und Energie
Bundesministerium für Bildung und Forschung

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