New muon spin rotation/relaxation measurements of the non-centrosymmetric superconductor LaNiC<sub>2</sub>

ORAL

Abstract

Non-centrosymmetric superconductors (NCSs) lack inversion center in their crystal structure, and consequently one of the typical symmetries for the formation of Cooper pairs. The absence of inversion symmetry strongly influences the Cooper pairing states possible in these materials. Here we report a muon spin rotation/relaxation (μSR) study of LaNiC2 single crystals, a non-magnetic, NCS with weak electronic correlations and a superconducting transition temperature, Tc ~ 2.7 K. Previous zero-field μSR measurements on a pressed pellet of LaNiC2 powder revealed the onset of spontaneous magnetic fields at Tc. This finding signifies time-reversal symmetry breaking (TRSB) in superconducting phase, which is compatible with a non-unitary triplet-pairing state. However, other kinds of experiments have provided evidence for conventional BCS s-wave pairing, point nodes in the gap function and even two-gap superconductivity. Our new μSR investigation of LaNiC2 provides a fresh perspective on the nature of the superconducting pairing state, by yielding the temperature and magnetic field dependencies of the magnetic penetration depth and vortex core size in the mixed state and through a new test of TRSB.

*Acknowledged support from NSERC and JSPS KAKENHI with grant nos. JP15K05156 and JP15KK0149

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Presenters

  • Shyam Sundar

    • Simon Fraser Univ
    • Physics, Simon Fraser University
    • Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

Authors

  • Shyam Sundar

    • Simon Fraser Univ
    • Physics, Simon Fraser University
    • Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

  • Sarah Dunsiger

    • CMMS, TRIUMF
    • TRIUMF
    • Centre for Molecular and Materials Science, TRIUMF, Vancouver, British Columbia V6T 2A3, Canada

  • Shayan Gheidi

    • Simon Fraser Univ
    • Physics, Simon Fraser University
    • Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

  • Krishant S Akella

    • Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

  • Andre M Côté

    • Simon Fraser Univ
    • Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada

  • Yoshiki J Sato

    • Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan

  • Takatsugu Koizumi

    • Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan

  • Rikio Settai

    • Department of Physics, Niigata University, Niigata 950-2181, Japan

  • Yusuke Hirose

    • Department of Physics, Niigata University, Niigata 950-2181, Japan

  • Ismardo Bonalde

    • Centro de Física, Instituto Venezolano de Investigaciones Cientificas, Apartado 20632, Caracas 1020-A, Venezuela

  • Fuminori Honda

    • Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan

  • Jeff Sonier

    • Simon Fraser Univ
    • Physics, Simon Fraser University
    • Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada