ITINERANT FERROMAGNETISM IN THE Y-NI-B-C SYSTEM

While Y3Ni7B2 exhibits Pauli paramagnetism, ferromagnetic-like (T-c = 36 K) behavior is observed in Y3Ni7B2C at 5 K and 50 kOe, the magnetiz ation is M(s) = 0.04 mu(B)/Ni. Above T-c, P-eff = 0.9 mu(B)/Ni. The P- eff/M(s) ratio is characteristic of itinerant magnetism. Mossbauer stu dies at 4.2 K of doped(57)Fe indicate that the Ni in superconducting Y Ni2B2C is not magnetic. Thus, the ferromagnetic mu SR signal found in RNi(2)B(2)C stems from an impurity phase of R(3)Ni(7)B(2)C.