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: | , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-05-01
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| Series: | Communications Materials |
| Online Access: | https://doi.org/10.1038/s43246-025-00833-z |
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| Summary: | 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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| ISSN: | 2662-4443 |