Superconducting—normal phase boundaries of (La,Th)Ce systems

The dependence of the superconducting transition temperature T_c on Ce impurity concentration n is reported for various ($\text{La, Th}$)Ce systems. These results document for the first time the evolution of the superconducting— normal phase boundary (T_c vs n curve) as an impurity undergoes magnetic- nonmagnetic transition which for Ce impurities in ($\text{La, Th}$)Ce systems proceeds with increasing Th concentration. Observed for only the second time, re-entrant T_c vs n curves are reported for two La-rich La, Th host compositions.