Magnetism in Nickel and Synchrotron Beam Polarization Studied by X-ray Diffraction

Abstract

The ratio of the magnetic to the charge form factors of nickel has been determined by white‐beam X‐­ray diffraction. The measurements were made on the new UK magnetic scattering beamline (XMaS) on a dipole source 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 previous studies. The data have been analysed using Hartree–Fock free‐ion wave functions and core electron polarization effects were included. The results support the interpretation of neutron data obtained at lower momentum transfer for the eg and t2g 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 extremely suitable source for studies of ferromagnetism.

Temperature dependence of the spin and orbital magnetization density inSm0.982Gd0.018AlTaylor1, Duffy2, Bebb3 et al. 2002Phys. Rev. BSelf Cite434360View full textAdd to dashboardCite

“…In this investigation a monochromatic beam was used to avoid these uncertainties. However the principle remains identical to that described previously for white beam experiments [7], [8].…”

Absolute Spin Magnetic Moment ofFeF2from High Energy Photon Diffraction

“…Results from this technique have been published for different materials [1][2][3][4]. For ferromagnetic materials other methods exist such as magnetic x-ray circular dichroism (MXCD) [5][6][7], which strongly rely on theoretical models available, or x-ray diffraction using circularly polarized x rays [8,9].…”

“…Results from this technique have been published for different materials [1][2][3][4]. For ferromagnetic materials other methods exist such as magnetic x-ray circular dichroism (MXCD) [5][6][7], which strongly rely on theoretical models available, or x-ray diffraction using circularly polarized x rays [8,9].Here, we present results of a magnetic diffraction experiment on antiferromagnetic FeF 2 with 115 keV photons, where the magnetic scattering cross section depends only on the spin component perpendicular to the diffraction plane and which is independent from the polarization of the x rays. This allows one to measure the absolute spin magnetic moment without polarization analysis.…”

The XMaS beamline at ESRF: instrumental developments and high-resolution diffraction studies

“…In order to allow studies of ferromagnets, using circularly polarised radiation, unfocused white beam is provided for. This facility was exploited at an early stage of construction (Laundy et al, 1998). The diffractometer can be used with focused or unfocused beam, the latter providing higher wave vector resolution.…”

“…The experimental technique uses the suppression of charge scattering at 90º in the orbital plane of the synchrotron to maximise the ratio of magnetic to charge scattering. In fact the experiment is carried out with the white beam extracted at an angle between 2 µ rad and 10 µ rad above or below the orbital plane and the energy-sensitive detector at 90º horizontally (Laundy et al, 1998). The magnetic field is aligned alternately parallel and antiparallel to the incident beam direction.…”