195Pt NMR study in U(Pt1-xPdx)3

Pt-195 NMR study has been performed in U(Pt1-xPdx)(3). The hyperfine coupling constant of Pt-195 was obtained to be -85 kOe/mu(B) in U(Pt1-xPdx)(3) for 0 less than or equal to x less than or equal to 0.05. The large transferred field arises from the spin polarization of the Pt 4d-electron induced by the magnetic moment of U 5f-electrons. In the antiferromagnetically ordered (AF) state of U(Pt0.95Pd0.05)(3), which has the ordered moment of 0.65 mu(B), the NMR spectrum in zero field has shown the existence of an internal field of about 30 kOe. Since the magnetic structures of UPt3 and U(Pt0.95Pd0.05)(3) proposed by the neutron diffraction experiment are the same, an appearance of the internal held is also expected in UPt3. However, the internal held associated with a tiny moment (0.02 mu(B)) has never been observed in UPt3. This result has shown that the AF order in UPt3 is not static but fluctuating. (C) 1998 Elsevier Science B.V. All rights reserved.