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Ufe(2) (Laves phase, fcc crystal structure) is a ferromagnet with T(C) = 165 K. Previous neutron elastic measurements have established that the Fe moment is 0.6 mB and that the moment on the U atom is almost zero. We have examined the spin dynamics from a large single crystal with both thermal and cold-source triple-axis spectrometers. Comparisons with the extensive work performed on Rfe(2) suggest that two dispersive modes should be seen at low energy. However, only one mode has been found in Ufe(2) and this involves the precession of the Fe spins. We propose that the acoustic mode involving the uranium spin is sufficiently broadened that we cannot readily detect the excitation. Nevertheless, the influence of the U-Fe exchange may be seen in the presence of a gap in the Fe spin-wave spectrum at q=0, and in an increase in an increase in the Fe spin-wave stiffness constant as compared to that found in pure Fe. We find also that D is strongly temperature dependent, presumably due to two magnon interactions. This effect, together with the low moment on the Fe atoms, results in the comparatively low TC of 165 K.

Additional information

Authors: PAOLASINI L ET AL, CEA, CEN Grenoble (FR);LANDER G H, JRC Karlsruhe (DE);SHAPIRO S M, Brookhaven National Laboratory, Physics Department, New York (US);CACIUFFO R, Università di Ancona, Dipartimento di Scienze dei Materiali é della Terra (IT);LEBECH B, Risø National Laboratory, Physics Department, Roskilde (DK);ROESSLI, Institut Laue-Langevin, Grenoble (FR);FOURNIER J-M, Université J. Fourier, Grenoble (FR)
Bibliographic Reference: Article : Phys. Rev. B Condens. Matter (1996)
Record Number: 199610761 / Last updated on: 1996-08-16
Original language: en
Available languages: en