SUPERCONDUCTING PHASE-TRANSITIONS IN ERCY1-CRH4B4

The superconducting transition temperature Tc1 and the reentering temperature Tc2 to the normal ferromagnetically ordered state in the system ErcY1-cRh4B4 were determined as a function of the concentration of Er. Comparing our results with the recent theory of Maekawa et al., the exchange interactions J′ among local spins and I between local spins and superconducting electrons were estimated as J′ {equal to or succeeds} 0.30 K and I2 N(0) {equal to or succeeds} 0.046 K, where N(0) is the density of states. A sudden decrease of Hc2 at Tc2 was observed in a high concentration region suggesting the first order transition. © 1979.