Superconducting gap symmetry of the noncentrosymmetric superconductor W3Al2C

Abstract

A detailed zero-field and transverse-field muon spin relaxation/rotation ($\mu$SR) experiemnts have been carried out on the recently discovered non-centrosymmetric superconductor W${}_3$Al${}_2$C to speculate about its superconducting ground state. Bulk nature of superconductivity below 7.6 K is confirmed through magnetization measurements. No change in the $\mu$SR spectra collected above and below $T_c$ is visible, ruling out the possibility of spontaneous magnetic field below $T_c$. This confirms that time-reversal symmetry is preserved for W${}_3$Al${}_2$C upon entering in the superconducting ground state. Temperature dependent superfluid density [${\rho }_s(T)$], which directly reflects the superconducting gap symmetry is obtained by the analysis of spectra obtained from the transverse-field $\mu$SR experiments. Despite a non-centrosymmetric structure, W${}_3$Al${}_2$C adopts a fully gaped spin-singlet superconducting ground state with a zero temperature value of gap ${\Delta }_0$ = 1.158(8) meV with gap-to-$T_c$ ratio 2${\Delta }_0/k_B{T}_c\approx$3.54, classifying this material as a weakly-coupled superconductors.

6 pages, 5 figures

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• Polar charge density wave in a superconductor with crystallographic chirality
• Type-II superconductivity in the Dirac semimetal PdTe2
• $s$-wave superconductivity in the noncentrosymmetric W${}_3$Al${}_2$C superconductor: An NMR study
• Superconductivity in W3Re2C with chiral structure