Vortex Lattice Anisotropy in Sr$_2$RuO$_4$ with $H \parallel a$

ORAL

Abstract

We have studied the vortex lattice (VL) in superconducting Sr$_2$RuO$_4$ using spin-polarized small-angle neutron scattering (SP-SANS) and with magnetic fields ($H$) close to, but not perfectly aligned with, the crystalline basal plane. In this configuration the VL possesses a large transverse field component, due to the large anisotropy of Sr$_2$RuO$_4$, which greatly increases the spin-flip SANS scattered intensity. Bragg reflections indicative of a highly distorted hexagonal VL were observed, and an analysis of the magnitude of the scattering vector yielded an anisotropy of $50 - 60$, roughly two times the $H_{c2}$ anisotropy. We discuss implications of this result in relation to theoretical predictions of Pauli paramagnetic effects in Sr$_2$RuO$_4$ with $H \perp c$ [K. Machida and M. Ichioka, Phys. Rev. B {\bf 77}, 184515 (2008)].

*This work was supported by the Department of Energy, Basic Energy Sciences under Award No. DE-FG02-10ER46783.

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Authors

  • Morten Eskildsen

    • University of Notre Dame, IN, USA
    • University of Notre Dame
    • Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA

  • C. Rastovski

    • University of Notre Dame, IN, USA

  • C.D. Dewhurst

    • Institut Laue-Langevin, France

  • W.J. Gannon

    • Northwestern University, IL, USA

  • D.C. Peets

    • Kyoto University, Japan

  • H. Takatsu

    • Kyoto University, Japan

  • Y. Maeno

    • Kyoto University, Japan