ID20 Magnetic Scattering Beamline

Contact Tel: +33(0)47688 +ext Luigi PAOLASINI, Scientist in charge 2402 Claudio MAZZOLI, Scientist 2970 ID20 Control Hutch 2643 ID20 Control Hutch 2644 Contact us (e-mail) Staff

Beamline ID20 Magnetic Scattering was closed on 05/05/2011. A new beamline will be built at ID20 within the Upgrade Programme.  

The beamline ID20 is optimised for the study of electronic and magnetic properties of solids, in particular magnetic, charge and orbital ordering. The versatility of this beamline makes it unique in the conception and implementation of new ideas for experiments. The very recent developments in coherent magnetic scattering, orbital ordering, magnetic surface experiments and full polarisation control by the scientists of this beamline are just a few examples.

Two experimental hutches are available:

• EH1 hosts a Microcontrole vertical diffractometer with azimuth degree of freedom (4+1 circles); a series of displex cryostats provide temperature at the sample down to 1.6K;
• EH2 is equipped with a new Huber horizontal diffractometer, optimized for heavy load sample environment as the Oxford 10T superconducting split-coil cryomagnet (T > 2K).
  

The beamline is designed to achieve the following:

• a large tunable energy-range i.e. 3 keV < E < 30 keV;
• a very good energy resolution (i.e. E/E < 10-4) to scan an element's absorption edge;
• a high rate of harmonic rejection (<10-4) due to the use of two mirrors;
• a complete control of the incident x-ray polarisation via phase plates;
• linear polarization analysis of scattered photons;
• complex sample environments (low temperatures, pressure, high static magnetic fields).

Scientific Applications

X-ray magnetic scattering complement the magnetic neutron scattering technique regarding sample size, Q-resolution, single magnetic domain studies, separation of angular and spin contributions to the magnetic moment, and magnetic ordering of non-suitable, highly neutron absorbing, compounds. Moreover, the site and shell selectivity of x-ray resonant scattering allow for the exploration of the anisotropic properties of atomic scattering tensors, and thus represent an unique method to characterize magnetic interactions from electronic point of view.

Techniques Available

Polarization analysis

The state of linear polarization of the scattered beam may be determined by the use of an analyzer crystal with scattering angle of approximately 90 degrees. A large set of such crystals, covering a wide energy range, is available. Furthermore, the polarization of the incident beam may be modified with an x-ray phase plate.

Non Resonant magnetic x-ray scattering (NRMXS)

Quantitative information on the orbital magnetic moment can be obtained by the linear polarization analysis of scattered photons. By tuning the incident photon energy far from any absorption edge, and measuring the ratio of scattered polarization state on a magnetic Bragg satellite, either parallel (p) or perpendicular (s) to the scattering plane, it is possible to extract information on ratio of orbital and spin magnetic moment, L/S.

Resonant x-ray scattering (RXS)

Large resonant enhancements of the scattering cross section may be observed when the incident photon energy is tuned close to an atomic absorption edge, e.g., the M4,5 edges of actinides, the L2,3 edges of rare earths, or the K edges of transition metals. Resonances sensitive to magnetic and quadrupolar order have been observed. The resonant cross section has a characteristic polarization dependence, which may be exploited to obtain further information on the magnetic moment direction and the space group of the ordered state. The technique is particularly powerful when polarization analysis of the scattered beam is used in combination with azimuthal scans, where the sample is rotated about the scattering vector.