MAGNETISM IN NICKEL AND SYNCHROTRON BEAM POLARIZATION STUDIED BY X-RAY-DIFFRACTION

The ratio of the magnetic to the charge form factors of nickel has bee n determined by white-beam X-ray diffraction. The measurements were ma de on the new UK magnetic scattering beamline (XMaS) on a dipole sourc e at the ESRF The data comprise the three (h,h,0) reflections (4,4,0), (6,6,0) and (8,8,0) and the seven high-order (h,0,0) reflections (6,0 ,0) to (18,0,0), which doubles the range of wavevectors compared to pr evious studies. The data have been analysed using Hartree-Fock free-io n wave functions and core electron polarization effects were included. The results support the interpretation of neutron data obtained at lo wer momentum transfer for the e(g) and t(2g) orbital occupancies. The polarization of the dipole source is deduced to vary from 99.88 to 99. 83% between 5 and 15 keV, respectively. This high value makes it an ex tremely suitable source for studies of ferromagnetism.