Multi-Band Analysis on Physical Properties of the Quasi-Two-Dimensional Superconductor NbSe2

The discovery of quasi-two-dimensional superconductors bears consequences for both basic research and practical applications. However, the mechanism of superconductivity and the form of order parameters are still controversial problems for the transition metal dichalcogenide NbSe2 thin film. Under the Neumann boundary condition, the physical properties of this compound are investigated within the two-component Ginzburg-Landau theory. We compute the upper critical field in an arbitrary direction and the temperature dependence of critical supercurrent density through this layered system. All of our theoretical calculations fit the experimental measurements well; thus, this study strongly provides evidence of two-gap s-wave superconductivity in the NbSe2 thin film.