NEW CLUES FOR UNDERSTANDING THE MAGNETIC-BEHAVIOR OF UPT3

We present results of a fairly complete study on which dopants M resul t in single-phase U(1-x)M(x)Pt(3) samples. The resulting new samples, M = Y, Lu, Sc, Hf, Zr, have been characterized by low temperature magn etic susceptibility and specific heat for x less than or equal to 0.07 . Based on a previously proposed model, the cin ratios of the present alloys would be expected to result in magnetic behavior as observed in U1-xThxPt3 and U(Pt1-xPdx)(3). On the contrary, no magnetism is found ; the Sc-doped samples actually show a suppression of spin fluctuation s. A new proposal is made to explain which properties are critical for the magnetic behavior of UPt3, as well as its doped derivatives.