Magnetically controlled vortex dynamics in a ferromagnetic superconductor

Abstract Ferromagnetic superconductors are exceptionally rare because the strong ferromagnetic exchange field usually destroys singlet superconductivity. EuFe2(As1−x P x )2, an iron-based superconductor with a maximum critical temperature of 25 K, uniquely exhibits full coexistence with ferromagneti...

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Main Authors: Joseph Alec Wilcox, Lukas Schneider, Estefani Marchiori, Vadim Plastovets, Alexandre Buzdin, Pardis Sahafi, Andrew Jordan, Raffi Budakian, Tong Ren, Ivan Veshchunov, Tsuyoshi Tamegai, Sven Friedemann, Martino Poggio, Simon John Bending
Format: Article
Language:English
Published: Nature Portfolio 2025-05-01
Series:Communications Materials
Online Access:https://doi.org/10.1038/s43246-025-00833-z
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author Joseph Alec Wilcox
Lukas Schneider
Estefani Marchiori
Vadim Plastovets
Alexandre Buzdin
Pardis Sahafi
Andrew Jordan
Raffi Budakian
Tong Ren
Ivan Veshchunov
Tsuyoshi Tamegai
Sven Friedemann
Martino Poggio
Simon John Bending
author_facet Joseph Alec Wilcox
Lukas Schneider
Estefani Marchiori
Vadim Plastovets
Alexandre Buzdin
Pardis Sahafi
Andrew Jordan
Raffi Budakian
Tong Ren
Ivan Veshchunov
Tsuyoshi Tamegai
Sven Friedemann
Martino Poggio
Simon John Bending
author_sort Joseph Alec Wilcox
collection DOAJ
description Abstract Ferromagnetic superconductors are exceptionally rare because the strong ferromagnetic exchange field usually destroys singlet superconductivity. EuFe2(As1−x P x )2, an iron-based superconductor with a maximum critical temperature of 25 K, uniquely exhibits full coexistence with ferromagnetic order below T FM ≃ 19 K. The interplay leads to narrowing of ferromagnetic domains at higher temperatures and spontaneous nucleation of vortices/antivortices at lower temperatures. Here we demonstrate how the underlying magnetic structure controls the superconducting vortex dynamics in applied magnetic fields. Just below T FM we observe a pronounced peak in the creep activation energy, and magnetic force microscopy measurements reveal the presence of very closely spaced (w ≪ λ) vortex clusters. We attribute these observations to the formation of vortex polarons, for which we present a theoretical description. In contrast, we link strong magnetic irreversibility at low temperatures to a critical current governed by giant flux creep over an activation barrier for vortex-antivortex annihilation near domain walls. Our work suggests new routes for the magnetic enhancement of vortex pinning with important applications in high-current conductors.
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spelling doaj-art-e4291ba7979b49579863a002eb84ecd62025-08-20T02:03:36ZengNature PortfolioCommunications Materials2662-44432025-05-016111110.1038/s43246-025-00833-zMagnetically controlled vortex dynamics in a ferromagnetic superconductorJoseph Alec Wilcox0Lukas Schneider1Estefani Marchiori2Vadim Plastovets3Alexandre Buzdin4Pardis Sahafi5Andrew Jordan6Raffi Budakian7Tong Ren8Ivan Veshchunov9Tsuyoshi Tamegai10Sven Friedemann11Martino Poggio12Simon John Bending13Department of Physics, University of BathDepartment of Physics, University of BaselDepartment of Physics, University of BaselUniversity of BordeauxUniversity of BordeauxDepartment of Physics and Astronomy, University of WaterlooDepartment of Physics and Astronomy, University of WaterlooDepartment of Physics and Astronomy, University of WaterlooDepartment of Applied Physics, The University of TokyoDepartment of Applied Physics, The University of TokyoDepartment of Applied Physics, The University of TokyoH. H. Wills Physics Laboratory, University of BristolDepartment of Physics, University of BaselDepartment of Physics, University of BathAbstract Ferromagnetic superconductors are exceptionally rare because the strong ferromagnetic exchange field usually destroys singlet superconductivity. EuFe2(As1−x P x )2, an iron-based superconductor with a maximum critical temperature of 25 K, uniquely exhibits full coexistence with ferromagnetic order below T FM ≃ 19 K. The interplay leads to narrowing of ferromagnetic domains at higher temperatures and spontaneous nucleation of vortices/antivortices at lower temperatures. Here we demonstrate how the underlying magnetic structure controls the superconducting vortex dynamics in applied magnetic fields. Just below T FM we observe a pronounced peak in the creep activation energy, and magnetic force microscopy measurements reveal the presence of very closely spaced (w ≪ λ) vortex clusters. We attribute these observations to the formation of vortex polarons, for which we present a theoretical description. In contrast, we link strong magnetic irreversibility at low temperatures to a critical current governed by giant flux creep over an activation barrier for vortex-antivortex annihilation near domain walls. Our work suggests new routes for the magnetic enhancement of vortex pinning with important applications in high-current conductors.https://doi.org/10.1038/s43246-025-00833-z
spellingShingle Joseph Alec Wilcox
Lukas Schneider
Estefani Marchiori
Vadim Plastovets
Alexandre Buzdin
Pardis Sahafi
Andrew Jordan
Raffi Budakian
Tong Ren
Ivan Veshchunov
Tsuyoshi Tamegai
Sven Friedemann
Martino Poggio
Simon John Bending
Magnetically controlled vortex dynamics in a ferromagnetic superconductor
Communications Materials
title Magnetically controlled vortex dynamics in a ferromagnetic superconductor
title_full Magnetically controlled vortex dynamics in a ferromagnetic superconductor
title_fullStr Magnetically controlled vortex dynamics in a ferromagnetic superconductor
title_full_unstemmed Magnetically controlled vortex dynamics in a ferromagnetic superconductor
title_short Magnetically controlled vortex dynamics in a ferromagnetic superconductor
title_sort magnetically controlled vortex dynamics in a ferromagnetic superconductor
url https://doi.org/10.1038/s43246-025-00833-z
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