Melting of the 2D vortex lattice in thin <i>a</i>-MoGe films

ORAL

Abstract

The vortex lattice in a 2D type II superconductor is expected to melt via a BKT transition that involves an intermediate liquid phase (“hexatic fluid”), which preserves orientational order. Recent experiments combining transport and STM imaging made it possible to identify the hexatic state in a-MoGe thin films, showing that vortex diffusivity in the hexatic fluid state is strongly reduced with respect to the isotropic vortex liquid. To fully characterize the melting transition, we performed systematic transport measurements on weakly disordered, 22 nm-thick a-MoGe films down to 0.020 K and in magnetic fields up to 18 T. Our results unambiguously show that the persistence of orientational correlations in the hexatic phase significantly slows down the vortex motion, leading to vanishingly small flux-flow resistance. This effect is consistent with numerical simulations.

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Supported by NSF DMR-1707785 and NHMFL via NSF DMR-1644779 and the State of
Florida.

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Presenters

  • Bal Pokharel

    • Department of Physics and National High Magnetic Field Lab, Florida State University
    • Dept. of Phys. & Natl. High Magnetic Field Lab., Florida State University

Authors

  • Bal Pokharel

    • Department of Physics and National High Magnetic Field Lab, Florida State University
    • Dept. of Phys. & Natl. High Magnetic Field Lab., Florida State University

  • Jasminka Terzic

    • Department of Physics and National High Magnetic Field Lab, Florida State University
    • Dept. of Phys. & Natl. High Magnetic Field Lab., Florida State Univ.
    • Dept. of Phys. & Natl. High Magnetic Field Lab., Florida State University

  • Dragana Popovic

    • Department of Physics and National High Magnetic Field Lab, Florida State University
    • Dept. of Phys. & Natl. High Magnetic Field Lab., Florida State Univ.
    • Dept. of Phys. & Natl. High Magnetic Field Lab., Florida State Univ
    • Dept. of Phys. & Natl. High Magnetic Field Lab., Florida State University

  • Surajit Dutta

    • Tata Institute of Fundamental Research

  • John Jesudasan

    • TIFR, Mumbai, India
    • Tata Institute of Fundamental Research

  • Pratap Raychaudhuri

    • Tata Institute of Fundamental Research
    • TIFR, Mumbai, India

  • Illaria MACCARI

    • KTH-Royal Institute of Technology

  • Lara Benfatto

    • Physics, "Sapienza'' University of Rome
    • Univ of Rome La Sapienza
    • Sapienza University of Rome, Italy
    • Dept. of Phys., Sapienza Univ. of Rome