Majorana modes in graphene strips: polarization, wavefunctions, disorder, and Andreev states

Fuente: arXiv
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Autores principales: Karoliya, Shubhanshu, Tewari, Sumanta, Sharma, Gargee
Formato: Preprint
Publicado: 2025
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author Karoliya, Shubhanshu
Tewari, Sumanta
Sharma, Gargee
author_facet Karoliya, Shubhanshu
Tewari, Sumanta
Sharma, Gargee
contents Topologically protected Majorana zero modes (MZMs) have attracted intense interest due to their potential application in fault-tolerant quantum computation (TQC). Graphene nanoribbons, with tunable edge terminations and compatibility with planar device architectures, offer a promising alternative to semiconductor nanowires. Here we present a comprehensive theoretical study of finite graphene strips with armchair, zigzag, and nearly square geometries, proximitized by an s-wave superconductor and subject to Rashba spin-orbit coupling, Zeeman fields, and disorder. Using exact diagonalization of the Bogoliubov-de Gennes tight-binding Hamiltonian, we analyze Majorana polarization, low-energy spectra, and real-space wavefunctions to identify the non-trivial topological phases supporting MZMs and distinguish them from from partially separated Andreev bound states (psABS) or the quasi-Majoranas. We systematically chart the robustness of these modes across geometries and disorder regimes, finding that armchair strips with short zigzag edges provide the most stable platform. Our results unify polarization diagnostics with spatial wavefunction analysis and disorder effects, yielding concrete design guidelines for graphene-based topological superconductors.
format Preprint
id arxiv_https___arxiv_org_abs_2511_22713
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Majorana modes in graphene strips: polarization, wavefunctions, disorder, and Andreev states
Karoliya, Shubhanshu
Tewari, Sumanta
Sharma, Gargee
Mesoscale and Nanoscale Physics
Topologically protected Majorana zero modes (MZMs) have attracted intense interest due to their potential application in fault-tolerant quantum computation (TQC). Graphene nanoribbons, with tunable edge terminations and compatibility with planar device architectures, offer a promising alternative to semiconductor nanowires. Here we present a comprehensive theoretical study of finite graphene strips with armchair, zigzag, and nearly square geometries, proximitized by an s-wave superconductor and subject to Rashba spin-orbit coupling, Zeeman fields, and disorder. Using exact diagonalization of the Bogoliubov-de Gennes tight-binding Hamiltonian, we analyze Majorana polarization, low-energy spectra, and real-space wavefunctions to identify the non-trivial topological phases supporting MZMs and distinguish them from from partially separated Andreev bound states (psABS) or the quasi-Majoranas. We systematically chart the robustness of these modes across geometries and disorder regimes, finding that armchair strips with short zigzag edges provide the most stable platform. Our results unify polarization diagnostics with spatial wavefunction analysis and disorder effects, yielding concrete design guidelines for graphene-based topological superconductors.
title Majorana modes in graphene strips: polarization, wavefunctions, disorder, and Andreev states
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2511.22713