Effect of Lanthanide Ion Substitutions for Lanthanum Sites on Superconductivity of (La1-xSrx)2CuO4-δ

Abstract

By substituting various lanthanide ions for La sites up to 90% level, the effect of foreign magnetic ions on the superconductivity of (La_1-x Sr _x )₂CuO_4-δ was examined. None of the 4f transition metal ions at 5% substitution level substantially destroyed the superconductivity, while a strong correlation was observed between the total spin of the 4f magnetic ions and the superconducting critical temperature, suggesting the exchange interaction between the conduction electrons and the 4f shell spins.