Superconducting properties of noncentrosymmetric superconductorCaIrSi3investigated by muon spin relaxation and rotation

Abstract

We have employed muon spin relaxation and rotation (µSR) to investigate the superconducting properties of the noncentrosymmetric superconductor CaIrSi 3 . Measurements of single-crystal specimens confirm the development of a robust superconducting state below T c = 3.55 ± 0.1 K with a ground-state magnetic penetration depth of λ L = 288 ± 10 nm and a coherence length of ξ = 28.8 ± 0.1 nm. The temperature evolution of the superfluid density indicates a nodeless superconducting gap structure dominated by an isotropic spin-singlet component in the dirty limit, with a carrier density of n = (4.6 ± 0.2) × 10 22 cm −3 as determined by Hall resistance measurements. We find no evidence of spontaneous time-reversal symmetry breaking in the superconducting state within an accuracy of 0.05 G. These observations suggest that the influence of any spin-triplet pairing component or multiple gap structure associated with noncentrosymmetric physics is very weak or entirely absent in CaIrSi 3 .

Time-reversal symmetry breaking in the noncentrosymmetric Zr3Ir superconductor

“…The coherence length ξ 0 is slightly larger than the electronic mean free path l e (see Table SIII in the Supplemental Material), implying that Zr 3 Ir is a superconductor in the dirty limit. Thus, similar to other NCSCs [37], the temperature dependence of its superfluid density was also analyzed by a dirty-limit model, which yields a gap value of 0.23(1) meV, slightly smaller than the clean-limit value, but consistent with previous studies [38].…”

Unconventional scaling of the superfluid density with the critical temperature in transition metal dichalcogenides

“…This very small effect of compression can be attributed to the unique anisotropy resulting from the stacking of layers with van der Waals type interactions between them. Thus, in view of the short coherence length and relatively large l , we can reliably assume that 2H-NbSe 2 lies close to the clean limit ( 30 , 49 ). With this assumption, we obtain the ground-state value n s /( m */ m e ) ≃ 5.7 × 10 27 m −3 and 7.5 × 10 27 m −3 for p = 0 and 2.2 GPa, respectively.…”

Investigations of the superconducting ground state of Zr3Ir : Introducing a new noncentrosymmetric superconductor

“…At this point, it will be worth it to discuss the dirty limit nature of the sample which can have implications on the measurements determining the superconducting gap structure, as done in Ref. [49]. A superconductor in the dirty limit regime will have an increased scattering from impurities and defects.…”