Spin Polarized Triplet Supercurrent in Ferromagnetic-Superconducting Josephson Junctions

ORAL

Abstract

Proximity coupling across superconductor-ferromagnet bilayers can give rise to the triplet component of the superconducting condensate [1]. Superconductivity and ferromagnetism have been reported to coexist in a Ni/Bi bilayer system [2]. We investigated Josephson and quasiparticle tunneling across such ferromagnetic-superconducting layers in Bi/Ni/Insulator/Ni/Bi junctions. The superconductivity in the Ni/Bi bilayer is expected to be topological [3]. Moreover, the observed Josephson current could be spin polarized, as superconducting quasiparticles originating from Ni in the Ni/Bi bilayer have been shown to also exhibit spin polarization [2]. The occurrence of conductance at zero bias in these junctions points to odd-frequency symmetry in the superconducting condensate, supporting the presence of a non-zero component associated with a triplet pair superconductivity insensitive to disorder.
1. F. S. Bergeret, A. F. Volkov, and K. B. Efetov, Phys. Rev. Lett. 86 (2001).
2. P. LeClair, J. S. Moodera, J. Philip, and D. Heiman, Phys. Rev. Lett. 94 (2005).
3. F. Schindler et al., Nat. Phys.14 (2018).
4. T. Yokoyama, Y. Tanaka, and N. Nagaosa, Phys. Rev. Lett. 106 (2011).

*We acknowledge funding from NSF (DMR-1700137) and ONR (N00014-16-1-2657) as well as MIT UROP funding.

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Presenters

  • Madison Sutula

    • Physics, Materials Science and Engineering, Massachusetts Institute of Technology

Authors

  • Madison Sutula

    • Physics, Materials Science and Engineering, Massachusetts Institute of Technology

  • Mirko Rocci

    • Plasma Science and Fusion Center and Francis Bitter Magnet Laboratory, MIT
    • Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology

  • Niladri Banerjee

    • Physics, Loughborough University

  • Cui-Zu Chang

    • Pennsylvania State University
    • Physics, Penn State University
    • Department of Physics, Pennsylvania State University
    • Physics, The Pennsylvania State University
    • Department of Physics, The Pennsylvania State University

  • F. Sebastian Bergeret

    • Centro de Fisica de Materiales CFM, Centro Mixto CSIC-UPV/EHU
    • Centro de Fisica de Materiales, CSIC-UPV/EHU, San Sebastian, Spain

  • Jagadeesh Moodera

    • Dept. Of Physics, Plasma Science and Fusion Center and Francis Bitter Magnet Lab, Massachusetts Institute of Technology
    • MIT
    • Department of Physics, Massachusetts Institute of Technology
    • Massachusetts Institute of Technology
    • Department of Physics, Plasma Science and Fusion Center, and Francis Bitter Magnet Lab, Massachusetts Institute of Technology
    • Plasma Science and Fusion Center and Francis Bitter Magnet Laboratory, MIT
    • Plasma Science and Fusion Center, and Francis Bitter Magnet Laboratory, and Department of Physics, MIT
    • Francis Bitter Magnet Laboratory and Plasma Science and Fusion Center, MASSACHUSETTS INSTITUTE OF TECHNOLOGY
    • Plasma Science and Fusion Center and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology
    • Physics, Francis Bitter Magnet Laboratory, Plasma Science and Fusion Center, Massachusetts Institute of Technology
    • Department of Physics, MIT, Cambridge, MA, 02139