Quasi-one-dimensional electron systems display intrinsic instability towards long-range ordered phases at sufficiently low temperatures. The superconducting orders are of particular interest as they ...can possess either singlet or triplet pairing symmetry and frequently compete with magnetism. Here we report on muon spin rotation and relaxation (μSR) study of Rb2Mo3As3 characterised by one of the highest critical temperatures Tc=10.4 K among quasi-one-dimensional superconductors. The transverse-field μSR signal shows enhanced damping below Tc due to the formation of vortex lattice. Comparison of vortex lattice broadening against single gap s−, p− and d−wave models shows the best agreement for the s−wave scenario but with the anomalously small superconducting gap, Δ0, to Tc ratio of 2Δ0/kBTc=2.74(1). The alternative nodal p−wave or d−wave scenarios with marginally worse goodness of fit would yield more realistic 2Δ0/kBTc=3.50(2) and 2Δ0/kBTc=4.08(1), respectively, and thus they cannot be ruled out when accounting for the superconducting state in Rb2Mo3As3.
Quasi-one-dimensional electron systems display intrinsic instability towards long-range ordered phases at sufficiently low temperatures. The superconducting orders are of particular interest as they ...can possess either singlet or triplet pairing symmetry and frequently compete with magnetism. Here we report on muon spin rotation and relaxation (\(\mathrm{\mu}\)SR) study of Rb\(_2\)Mo\(_3\)As\(_3\) characterised by one of the highest critical temperatures \(T_{\rm c}=10.4\ \mathrm{K}\) among quasi-one-dimensional superconductors. The transverse-field \(\mathrm{\mu}\)SR signal shows enhanced damping below \(T_{\rm c}\) due to the formation of vortex lattice. Comparison of vortex lattice broadening against single gap \(s-\), \(p-\) and \(d-\)wave models shows the best agreement for the \(s-\)wave scenario but with the anomalously small superconducting gap, \(\Delta_0\), to \(T_{\rm c}\) ratio of \(2\Delta_0/k_{\rm B}T_{\rm c}=2.74(1)\). The alternative nodal \(p-\)wave or \(d-\)wave scenarios with marginally worse goodness of fit would yield more realistic \(2\Delta_0/k_{\rm B}T_{\rm c}=3.50(2)\) and \(2\Delta_0/k_{\rm B}T_{\rm c}=4.08(1)\), respectively, and thus they cannot be ruled out when accounting for the superconducting state in Rb\(_2\)Mo\(_3\)As\(_3\).
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