The Upper Critical Field of Bilayer NbSe2

ORAL

Abstract

We report on the fate of the superconducting state of bilayer NbSe$_2$ in a large parallel magnetic field. Due to strong spin-orbit coupling, the system exhibits an an out-of-plane polarization of electron spins in each valley, which leads to an enhanced upper critical field $H_{c2}^{||}$ as compared to that expected from the Pauli limit $H_p$ [1]. We explore the behavior of $H_{c2}^{||}(T)$ in the low temperature limit, down to $T = 0.3$K (approximately $0.06T_c$), and we find a maximum upper critical field of 28 T which is >3 times the Pauli limit. We find that the measured $H_{c2}^{||}(T)$ deviates significantly from the standard pair-breaking theory as $T \rightarrow 0$, and we compare our results to recent observations of Ising superconductivity in NbSe$_2$ [1] and in ionic-liquid-gated MoS$_2$ [2], as well as to calculations of $H_{c2}$ based on realistic band structure of NbSe$_2$. References: [1] Xi et al. arXiv:1507.08731 (2015) [2] Saito et al. arXiv:1506.04146 (2015)

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Authors

  • Benjamin Hunt

    • Carnegie Mellon University
    • Physics Department, Carnegie Mellon University ,Pittsburgh, PA 15213

  • Adam Tsen

    • Columbia University
    • University of Waterloo and Columbia University

  • Y. D. Kim

    • Columbia University

  • Z. J. Yuan

    • Peking University

  • S. Jia

    • Peking University

  • R. J. Cava

    • Princeton University

  • J. Hone

    • Columbia University

  • P. Kim

    • Harvard University

  • Abhay Pasupathy

    • Columbia university
    • Columbia Universtiy in the City of New York
    • Columbia Univ
    • Columbia University

  • Cory Dean

    • Columbia University
    • Department of Physics, Columbia University