Nonuniform superconducting states from Majorana flat bands

Fuente: arXiv
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Hauptverfasser: Varada, Sushanth, Kobiałka, Aksel, Bhattacharya, Ankita, Holmvall, Patric, Black-Schaffer, Annica M.
Format: Preprint
Veröffentlicht: 2026
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author Varada, Sushanth
Kobiałka, Aksel
Bhattacharya, Ankita
Holmvall, Patric
Black-Schaffer, Annica M.
author_facet Varada, Sushanth
Kobiałka, Aksel
Bhattacharya, Ankita
Holmvall, Patric
Black-Schaffer, Annica M.
contents Zero-energy flat bands within the superconducting gap can give rise to competing ordered phases. We investigate such phases in topological superconductors based on the magnetic adatom platform hosting a flat band of Majorana edge states. Our self-consistent calculations of the superconducting order parameter show the emergence of both a pair density wave with edge-localized amplitude modulations and a phase crystal characterized by edge-localized phase modulations. These two phases lower the free energy of the system by gapping out the Majorana flat band, as dictated by winding numbers, which are primarily tuned by the chemical potential. In fact, at zero temperature the uniform superconducting solution with Majorana flat band never survives and the phase diagram features a pair density wave, while the order parameter transitions into a phase crystal when amplitude modulations are insufficient to hybridize all the Majorana states. A broad intermediate region connects these two phases with comparable modulations in both amplitude and phase. At finite temperatures, the pair density wave survives up to around 80% of the bulk superconducting transition temperature, while the phase crystal only appears at lower temperatures and the intermediate region is strongly suppressed. Our findings establish the ubiquity of emergent nonuniform superconducting phases and their temperature-dependent behavior in topological superconductors.
format Preprint
id arxiv_https___arxiv_org_abs_2605_03859
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Nonuniform superconducting states from Majorana flat bands
Varada, Sushanth
Kobiałka, Aksel
Bhattacharya, Ankita
Holmvall, Patric
Black-Schaffer, Annica M.
Superconductivity
Mesoscale and Nanoscale Physics
Zero-energy flat bands within the superconducting gap can give rise to competing ordered phases. We investigate such phases in topological superconductors based on the magnetic adatom platform hosting a flat band of Majorana edge states. Our self-consistent calculations of the superconducting order parameter show the emergence of both a pair density wave with edge-localized amplitude modulations and a phase crystal characterized by edge-localized phase modulations. These two phases lower the free energy of the system by gapping out the Majorana flat band, as dictated by winding numbers, which are primarily tuned by the chemical potential. In fact, at zero temperature the uniform superconducting solution with Majorana flat band never survives and the phase diagram features a pair density wave, while the order parameter transitions into a phase crystal when amplitude modulations are insufficient to hybridize all the Majorana states. A broad intermediate region connects these two phases with comparable modulations in both amplitude and phase. At finite temperatures, the pair density wave survives up to around 80% of the bulk superconducting transition temperature, while the phase crystal only appears at lower temperatures and the intermediate region is strongly suppressed. Our findings establish the ubiquity of emergent nonuniform superconducting phases and their temperature-dependent behavior in topological superconductors.
title Nonuniform superconducting states from Majorana flat bands
topic Superconductivity
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2605.03859