2d van hove superconductors with weak and strong-couplings

The critical temperature (T centi grade) and the isotope coefficient (alpha) of two-dimensional van Hove superconductors have been analyzed. The phonon induced superconductors with both weak and strong couplings are considered. For weak coupling, the variation of T centi grade and alpha as a function of average phonon frequency, omega D, for three sets of pairing potential, V, shows that and decreases at nearly same rate with the increase of omega D; but T centi grade increases with increasing omega D but at different rates for different V. For strong coupling, the variation of T centi grade and alpha shows that smaller band width produces desirable results that are consistent with observation. (author)