Μsr Study of Unconventional Pairing Symmetry in the Quasi-1D Na2Cr3As3 Superconductor

We report the finding of a novel pairing state in a newly discovered superconductor Na2Cr3As3. This material has a non-centrosymmetric quasi-one-dimensional crystal structure and is superconducting at TC∼ 8.0 K. We find that the magnetic penetration depth data suggests the presence of a nodal line pz-wave pairing state with zero magnetic moment using transverse-field muon-spin rotation (TF-μSR) measurements. The nodal gap observed in Na2Cr3As3 compound is consistent with that observed in isostructural (K,Cs)2Cr3As3 compounds using TF-μSR measurements. The observed pairing state is consistent with a three-band model spin-fluctuation calculation, which reveals the Sz=0 spin-triplet pairing state with the sinkz pairing symmetry. The long-sought search for chiral superconductivity with topological applications could be aided by such a novel triplet Sz=0p-wave pairing state.