Experimental signatures of nodeless multiband superconductivity in a 2H-Pd0.08TaSe2 single crystal

Abstract

In order to understand the superconducting gap nature of a 2H-Pd0.08TaSe2 single crystal with Tc=3.13K, in-plane thermal conductivity kappa, in-plane London penetration depth lambda L, and the upper critical fields Hc2 have been investigated. At zero magnetic field, it is found that no residual linear term kappa 0/T exists and lambda L follows a power-law Tn (T: temperature) with n = 2.66 at T <= Tc, supporting nodeless superconductivity. Moreover, the magnetic-field dependence of kappa 0/T clearly shows a shoulder-like feature at a low field region. The temperature dependent Hc2 curves for both in-plane and out-of-plane field directions exhibit clear upward curvatures near Tc, consistent with the shape predicted by the two-band theory and the anisotropy ratio between the Hc2(T) curves exhibits strong temperature-dependence. All these results coherently suggest that 2H-Pd0.08TaSe2 is a nodeless, multiband superconductor.