Broken time-reversal symmetry probed by muon spin relaxation in the caged type superconductor Lu${}_5$Rh${}_6$Sn${}_{18}$

Abstract

The superconducting state of the caged type compound Lu${}_5$Rh${}_6$Sn${}_{18}$ has been investigated by using magnetization, heat capacity, and muon-spin relaxation or rotation ($\mu$SR) measurements and the results interpreted on the basis of the group theoretical classifications of the possible pairing symmetries and a simple model of the resulting quasiparticle spectra. Our zero-field $\mu$SR measurements clearly reveal the spontaneous appearance of an internal magnetic field below the transition temperature, which indicates that the superconducting state in this material is characterized by the broken time-reversal symmetry. Further the analysis of temperature dependence of the magnetic penetration depth measured using the transverse field $\mu$SR measurements suggest an isotropic $s$-wave character for the superconducting gap. This is in agreement with the heat capacity behavior and we show that it can be interpreted in terms of a non unitary triplet state with point nodes and an open Fermi surface.

5 pages, 5 figures, SUPPLEMENTAL MATERIAL. appears in Physical Review B: Rapid Communications (2015)

References in corpus (7)

• High Resolution Polar Kerr Effect Measurements of Sr2RuO4: Evidence for Broken Time Reversal Symmetry in the Superconducting State
• Evidence for time-reversal symmetry breaking in the non-centrosymmetric superconductor LaNiC${}_2$
• Extremely strong-coupling superconductivity and anomalous lattice properties in the beta-pyrochlore oxide KOs2O6
• Direct Observation of Quadrupolar Excitons in the Heavy-Fermion Superconductor PrOs${}_4$Sb${}_{12}$
• Relativistic analysis of the pairing symmetry of the noncentrosymmetric superconductor LaNiC${}_2$
• Physical properties of noncentrosymmetric superconductor LaIrSi3: A μSR study
• Theory of Pairing Assisted Spin Polarization in Spin-Triplet Equal Spin Pairing: Origin of Extra Magnetization in Sr_2RuO_4 in Superconducting State