Magnetization, neutron, and resonant magnetic X-ray study of U(0.85)Th(0.15)Sb
The magnetic phase diagram of USb-ThSb solid solutions was first reported ten years ago, but crystals of U(0.85)Th(0.15)Sb have been re-examined using three different techniques following some unusual results first found with synchrotron X-rays. Magnetisation shows that T(N) is approximately 190 K but that a strong ferromagnetic moment develops below T(C) = 145 K and in high fields reaches 2.7Mu(B) per U atom at low temperature. Neutron diffraction indicates that the initial ordering near 190 K is incommensurate, q(inc) approximately 0.44 rlu. The ratio of the antiferromagnetic components is close to that expected for a square wave-modulation 4+,4-. q(inc) disappears near T(C) but a q = 1/2 component remains, which indicates the absence of a square-wave arrangement. Various models are presented. Synchrotron X-rays were also used to examine the crystal. At the M(IV) U resonance (3.73 keV) the magnetic scattering is easily observed. The structure is as before but the q = 1/2 component as observed by X-rays is larger. An interesting broadening of the transverse rocking width is seen at T(C) and ascribed to finite-size effects of the magnetic domains. This paper includes a discussion of the advantages of using synchrotron X-rays in studies of actinide magnetic structures, and demonstrates the complementarity of the three techniques.
Bibliographic Reference: Paper presented: 22. Journées des Actinides, Méribel (FR), April 22-24, 1992
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Record Number: 199210811 / Last updated on: 1994-12-02
Original language: en
Available languages: en