Gap symmetry of the noncentrosymmetric superconductor W3Al2C

Abstract

A detailed zero-field and transverse-field muon spin relaxation/rotation (μSR) experiments have been carried out on the recently discovered noncentrosymmetric superconductor W3Al2C to speculate about its superconducting ground state. Bulk nature of superconductivity below 7.6 K is confirmed through magnetization and specific heat measurements. No change in the zero field μSR spectra collected above and below Tc is visible, ruling out the possibility of spontaneous magnetic field below Tc. This confirms that time-reversal symmetry is preserved for W3Al2C upon entering in the superconducting ground state. Temperature-dependent superfluid density [ρs(T)], which directly reflects the superconducting gap symmetry is obtained by the analysis of spectra obtained from the transverse-field μSR experiments. Despite a noncentrosymmetric structure, W3Al2C adopts a fully gapped spin-singlet superconducting ground state as confirmed through the analysis of ρs(T) and Ce(T). The zero-temperature value of gap is Δ0 = 1.139(5) meV with gap-to-Tc ratio 2Δ0/kBTc≈3.48, classifying this material as a weakly coupled superconductors. We have also revealed that the ratio Tc/λeff−2 is comparable to the class of unconventional superconductors, which points towards an unconventional pairing mechanism in W3Al2C.

Source-reported materials — not catalogue approval

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