Letter | Published:

Universal lower limit on vortex creep in superconductors

Nature Materials volume 16, pages 409413 (2017) | Download Citation

Abstract

Superconductors are excellent testbeds for studying vortices, topological excitations that also appear in superfluids, liquid crystals and Bose–Einstein condensates. Vortex motion can be disruptive; it can cause phase transitions1, glitches in pulsars2, and losses in superconducting microwave circuits3, and it limits the current-carrying capacity of superconductors4. Understanding vortex dynamics is fundamentally and technologically important, and the competition between thermal energy and energy barriers defined by material disorder is not completely understood. Specifically, early measurements of thermally activated vortex motion (creep) in iron-based superconductors unveiled fast rates (S) comparable to measurements of YBa 2Cu3O7−δ (refs 5,6,7,8,9,10). This was puzzling because S is thought to somehow correlate with the Ginzburg number (Gi), and Gi is significantly lower in most iron-based superconductors than in YBa 2Cu3O7−δ. Here, we report very slow creep in BaFe 2(As0.67P0.33)2 films, and propose the existence of a universal minimum realizable S Gi1/2(T/Tc) (Tc is the superconducting transition temperature) that has been achieved in our films and few other materials, and is violated by none. This limitation provides new clues about designing materials with slow creep and the interplay between material parameters and vortex dynamics.

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Acknowledgements

This work was funded by the US DOE, Office of Basic Energy Sciences, Materials Sciences and Engineering Division (S.E., B.M. and L.C.). Sample fabrication was supported by the Japan Society for the Promotion of Science through the ‘Funding Program for World-Leading Innovation R&D on Science and Technology’. M.M. was supported by JSPS KAKENHI (26709076).

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Affiliations

  1. Condensed Matter and Magnet Science, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

    • S. Eley
    • , B. Maiorov
    •  & L. Civale
  2. Graduate School of Science and Technology, Seikei University, 3-3-1 Kichijoji-Kitamachi, Musashino-shi, Tokyo 180-8633, Japan

    • M. Miura

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Contributions

S.E. carried out the magnetization measurements, data analysis, and assisted with theoretical analysis. L.C. and B.M. designed the experiment, and L.C. spearheaded the theoretical analysis. S.E. and L.C. wrote the manuscript. M.M. grew and performed microstructural characterization on the films. All authors participated in editing the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to S. Eley.

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DOI

https://doi.org/10.1038/nmat4840

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