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Majorana bound states in encapsulated bilayer graphene
by Fernando Peñaranda, Ramón Aguado, Elsa Prada, Pablo San-Jose
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Pablo San-Jose |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202211_00049v2 (pdf) |
| Code repository: | https://github.com/fernandopenaranda/MBSinBLG |
| Date accepted: | 2023-01-17 |
| Date submitted: | 2022-12-29 12:52 |
| Submitted by: | San-Jose, Pablo |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approaches: | Theoretical, Computational |
Abstract
The search for robust topological superconductivity and Majorana bound states continues, exploring both one-dimensional (1D) systems such as semiconducting nanowires and two-dimensional (2D) platforms. In this work we study a 2D approach based on graphene bilayers encapsulated in transition metal dichalcogenides that, unlike previous proposals involving the Quantum Hall regime in graphene, requires weaker magnetic fields and does not rely on interactions. The encapsulation induces strong spin-orbit coupling on the graphene bilayer, which opens a sizeable gap and stabilizes fragile pairs of helical edge states. We show that, when subject to an in-plane Zeeman field, armchair edges can be transformed into p-wave one-dimensional topological superconductors by contacting them laterally with conventional superconductors. We demonstrate the emergence of Majorana bound states (MBSs) at the sample corners of crystallographically perfect flakes, belonging either to the D or the BDI symmetry classes depending on parameters. We compute the phase diagram, the resilience of MBSs against imperfections, and their manifestation as a 4$\pi$-periodic effect in Josephson junction geometries, all suggesting the existence of a topological phase within experimental reach.
List of changes
We added a new appendix with a new figure showing that any spin-independent perturbations, such as arbitrary edges and disorder, do not destroy the helical edge states in non-proximitized sample. We also added a small paragraph in the main text referencing the new discussion.
Published as SciPost Phys. 14, 075 (2023)
Reports on this Submission
Report #1 by Antonio Manesco (Referee 2) on 2023-1-2 (Invited Report)
Report
The authors now addressed the stability of helical modes in the presence of disorder. They have shown that realistic Rashba spin-orbit coupling strength leads to negligible spin mixing in the low-energy sector. Thus, scattering between the counter-propagating edge states is absent. They also have shown that the helical states are present for arbitrary crystal orientation of the boundaries.
Since all my questions and concerns were properly addressed, I recommend the publication of the manuscript as it is.