X-Ray Magnetic Scattering |
| M.J. Cooper Department of Physics, University of Warwick, Coventry CV4 7AL, UK |
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| Magnetic X-ray diffraction with synchrotron radiation is now an established technique for studies of antiferromagnets. The problems associated with the small magnetic scattering cross-section being alleviated by the dramatic enhancements found near absorption edges through resonant exchange scattering. The technique is particularly useful for those materials that require high wavevector resolution to reveal the structural phase transitions that accompany the magnetic ordering process or those that are difficult to investigate with neutrons, (e.g. samarium, for which recent results are presented). In the actinides the work is also motivated by the objective of performing an empirical separation of the spin and orbital components of magnetisation. Diffraction studies of ferromagnets require circular polarised radiation and suffer from the superposition of the small magnetic signal and the charge scattering; to date Laue methods have proved more successful than monochromatic beam studies. Ferro- and ferrimagnets can also be studied by Compton (inelastic) scattering but the cross-section is less well established: considerable effort has been directed to determining whether orbital magnetisation can be measured in these experiments and results on HoFe2 now indicate this is not so. Magnetic Compton profiles provide information about the momentum distribution of electrons with unpaired spins, and this, together with magnetisation data can provide the basis for the separation of spin and orbital magnetisation. |
| DOI: 10.12693/APhysPolA.82.137 PACS numbers: 61.10.Dp, 75.50.-y, 78.70.-g, 78.70.Ck |