High Tc Superconductivity of (La1-xSrx)2CuO4 –Effect of Substitution of Foreign Ions for Cu and La on Superconductivity

In order to elucidate the electronic structure of (La1-x Sr x )2CuO4, the sites of Cu and La were substituted with various 3d and 4f transition elements, respectively. The substitution on the Cu sites at 5 atomic percent level substantially destroyed the superconductivity whereas that on the La sites raised much less adverse effect. The results were discussed in terms of the two-dimensional conduction model based on the planar -Cu-O-Cu-O- linkage.