抄録
The relation between the superconducting critical temperature, Tc, and the effective pseudopotential radius, r(eff), was examined for elements, AB-type compounds, and Fe- and Cu-based compounds. Here, assuming arbitrarily their bonding states hybridized with valence electrons, we estimated r(eff) for the materials from the pseudopotential radii given for s, p, and d electrons. It is suggested that Tc can be estimated from the linear relation between Tc and N(v)r(eff)3, where N(v) is the effective number of valence electrons. For the elements with relatively high Tc such as Nb, Tc, and V, for those in AB compounds, and for Cu and Fe in their cuprates, pnictides, and chalcogenides, the value of Tc was found to vary almost linearly to N(v)r(eff)3 by assuming the p3dn or sp2dn hybridization. These findings suggest that the p3dn or sp2dn hybridization is a key bonding character to realize high Tc. For some of the compounds containing transition elements, however, the data deviate largely from the linear relation, indicating that the validity of the present argument is limited in such a category.
