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 [Tc and BC2 (0)] upon Sn intercalation. With a mere 4 mole% Sn intercalation, it is observed that Tc and BC2 (0) get suppressed by ~ 3.5 K and 3 T, respectively. Werthamer-Helfand-Hohenberg (WHH) analysis of magneto-transport data is performed to estimate BC2 (0). From the low temperature Raman scattering data in the normal phase of intercalated NbSe2, it is inferred that the suppression of superconductivity cannot be ascribed to strengthening of charge density wave (CDW)ordering. The effects such as electron-doping induced Fermi surface change and/or disorder scattering upon intercalation are speculated to be at play for the observed phenomena.