Nodeless bulk superconductivity in the time-reversal symmetry breaking Bi/Ni bilayer system

ORAL

Abstract

Epitaxial bilayer films of Bi(110) and Ni host a time-reversal symmetry (TRS) breaking superconducting order with an unexpectedly high transition temperature Tc = 4.1K. Using time-domain THz spectroscopy, we measure the low energy electrodynamic response of a Bi/Ni bilayer thin film from 0.2THz to 2THz as a function of temperature and magnetic field. We analyze the data in the context of a BCS-like superconductor with a finite normal-state scattering rate. In zero magnetic field, all states in the film become fully gapped, providing important constraints into possible pairing symmetries. Our data appears to rule out the odd-frequency pairing that is natural for many ferromagnetic-superconductor interfaces. By analyzing the magnetic field-dependent response in terms of a pair-breaking parameter, we determine that superconductivity develops over the entire bilayer sample which may point to the p-wave like nature of unconventional superconductivity.

*Experiments at JHU were supported by the Army Research Office Grant W911NF-15-1-0560. Film growth at Fudan was supported by the National Basic Research Program of China (Grants No. 2015CB921402 and No.2011CB921802), and the National Science Foundation of
China (Grants No. 11374057, No. 11434003, and No.11421404)

–

Presenters

  • Prashant Chauhan

    • Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, United States

Authors

  • Prashant Chauhan

    • Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, United States

  • Fahad Mahmood

    • Johns Hopkins University
    • Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, United States

  • Di Yue

    • Department of Physics, Fudan University, Shanghai, China
    • Department of Physics, Fudan University

  • Pengchao Xu

    • Department of Physics, Fudan University, Shanghai, China
    • Department of Physics, Fudan University

  • Xiaofeng Jin

    • Department of Physics, Fudan University, Shanghai, China
    • Department of Physics, Fudan University

  • Peter Armitage

    • Johns Hopkins University
    • Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD, United States
    • Department of Physics and Astronomy, Johns Hopkins University