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

In order to understand the superconducting gap nature of a 2H-Pd 0.08 TaSe 2 single crystal with T c = 3.13 K , in-plane thermal conductivity κ , in-plane London penetration depth λ L , and the upper critical fields H c 2 have been investigated. At zero magnetic field, it is found that no residual linear term κ 0 / T exists and λ L follows a power-law T n ( T : temperature) with n = 2.66 at T ≤ 1 3 T c , supporting nodeless superconductivity. Moreover, the magnetic-field dependence of κ 0 / T clearly shows a shoulder-like feature at a low field region. The temperature dependent H c 2 curves for both in-plane and out-of-plane field directions exhibit clear upward curvatures near T c , consistent with the shape predicted by the two-band theory and the anisotropy ratio between the H c 2 ( T ) curves exhibits strong temperature-dependence. All these results coherently suggest that 2H-Pd 0.08 TaSe 2 is a nodeless, multiband superconductor.