Evidence of a Nodal Line in the Superconducting Gap Symmetry of Noncentrosymmetric ThCoC_{2}

A Bhattacharyya; D T Adroja; K Panda; Surabhi Saha; Tanmoy Das; A J S Machado; O V Cigarroa; T W Grant; Z Fisk; A D Hillier; P Manfrinetti

doi:10.1103/PhysRevLett.122.147001

Evidence of a Nodal Line in the Superconducting Gap Symmetry of Noncentrosymmetric ThCoC_{2}

Phys Rev Lett. 2019 Apr 12;122(14):147001. doi: 10.1103/PhysRevLett.122.147001.

Authors

A Bhattacharyya^{1

2

3}, D T Adroja^{2

3}, K Panda¹, Surabhi Saha⁴, Tanmoy Das⁴, A J S Machado⁵, O V Cigarroa^{5

6}, T W Grant^{5

6}, Z Fisk⁶, A D Hillier², P Manfrinetti⁷

Affiliations

¹ Department of Physics, Ramakrishna Mission Vivekananda Educational and Research Institute, Belur Math, Howrah 711202, West Bengal, India.
² ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot Oxon, OX11 0QX, United Kingdom.
³ Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, P. O. Box 524, Auckland Park 2006, South Africa.
⁴ Department of Physics, Indian Institute of Science, Bangalore 560012, India.
⁵ Escola de Engenharia de Lorena, Universidade de São Paulo, P. O. Box 116, Lorena, São Paulo, 12602810.
⁶ Department of Physics and Astronomy, University of California-Irvine, Irvine, California 92697, USA.
⁷ Department of Chemistry, University of Genova, 16146 Genova, Italy.

PMID: 31050469
DOI: 10.1103/PhysRevLett.122.147001

Abstract

The newly discovered noncentrosymmetric superconductor ThCoC_{2} exhibits numerous types of unconventional behavior in the field dependent heat capacity data. Here we present the first measurement of the gap symmetry of ThCoC_{2} by muon spin rotation and relaxation (μSR) measurements. The temperature dependence of the magnetic penetration depth measured using the transverse field μSR experiment reveals the evidence of a nodal pairing symmetry. To understand this finding, we carry out calculations of the superconducting pairing eigenvalue and eigenfunction (pairing symmetry) due to the spin-fluctuation mechanism by directly implementing the ab initio band structures. We find that the system possesses a single Fermi surface with considerable three dimensionality and a strong nesting along the k_{z} direction. Such nesting promotes a superconducting state with a cosk_{z}-like pairing symmetry with a prominent nodal line on the k_{z}=±π/2 plane. The result agrees well with the experimental data.