MAGNETIC PAIR-BREAKING EFFECTS - MOMENT FORMATION AND CRITICAL DOPING LEVEL IN SUPERCONDUCTING LA1.85SR0.15CU1-XAXO4 SYSTEMS (A = FE, CO, NI, ZN, GA, AL)

We have conducted a systematic study on the effect of Cu-site doping in La1.85Sr0.15CuO4 system. The relations between Tc and doping level as well as the critical doping levels xc have been determined accurately for the Fe-, Co-, Ni-, Zn-, Ga-, and Al-doped systems. Every dopant either carries an intrinsic magnetic moment or induces a net moment on the Cu-O2 plane. The size of the moment is correlated with the suppression of superconductivity, consistent with the magnetic-pair-breaking effect. The ground states of the dopants have also been determined. © 1990 The American Physical Society.