The effect of Sn intercalation on the superconducting properties of 2H-NbSe2

2H-NbSe2 is known to be an archetype layered transitional metal dichalcogenide superconductor with a superconducting transition temperature of 7.3 K. In this article, we investigate the influence of Sn intercalation on superconducting properties of 2H-NbSe2. Sn being nonmagnetic and having no outer shell d-electrons unlike transition metals, one naively would presume that its effect on superconducting properties will be very marginal. However, our magnetic and transport studies reveal a significant reduction of both superconducting transition temperature and upper critical field [T-c and B-c2 (0)] upon Sn intercalation. With a mere 4 mole% Sn intercalation, it is observed that T-c and B-c2 (0) get suppressed by 3.5 K and 3 T, respectively. Werthamer-HelfandHohenberg (WHH) analysis of magneto-transport data is performed to estimate B-c2 (0). From the low temperature Raman scattering data in the normal phase of intercalated 2H-NbSe2, it is inferred that the suppression of superconductivity cannot be ascribed to strengthening of charge density wave (CDW) ordering. Rather, the weakening of superconductivity is attributed to the observed increase of c-axis lattice parameter and the possible changes in the Fermi surface upon Sn intercalation.