Single-crystal diffractometer with polarized neutrons POLI

  POLI Copyright: © IfK

The strength of the single crystal diffractometer POLI lies in the possibility of reliably measuring even very weak magnetic diffraction intensities using polarized neutrons and three-dimensional polarization analysis (CryoPAD). There is also an 8 Tesla magnet for spin-density determinations. This enables complex magnetic structures of crystals, magnetic domains and spatially resolved magnetization densities in magnetic materials to be determined with high accuracy. In combination with X-ray diffraction data, detailed investigations of the total electron density distributions as well as the density distributions of the unpaired electrons (spin-density distributions), which determine the magnetic behavior, are carried out.

Another typical area of application for POLI is crystal structure and magnetic structure analyzes under multiple external parameters such as e. g. temperature/magnetic field/electric field/pressure and their various combinations for researching complex phase diagrams in functional materials.

The development and construction of POLI were financially supported as part of the BMBF collaborative program "Research in condensed matter on large devices" from 2004 to 2016 (s. Finished projects). Since 2015, it has been operated jointly with the JCNS.

  Diffractometer POLI Copyright: © IfK
Technical features

Polarized/non-polarized neutrons with
wave lengths 0,55 Å < λ < 1,15 Å,
max. neutron flux > 2·107 n/cm2/s,
sample temperatures:
polarized 0,4 K < T < 420 K,
non-polarized 0,05 K < T < 2100 K,
magnetic field 0 - 8 T,
electric field 0 - 10 kV;
spherical neutron polarimetry

Application Crystal structure analysis under extreme conditions: very high/low temperatures, magnetic/electric fields, pressure; phase transitions.
Investigation of complex magnetic structures and domains.
Determination of magnetic form factors, spin densities and local magnetic anisotropies.
 

Further information for POLI can be found on the MLZ website.

Team:

N. N. (1st local contact)
Dr. Rajesh Dutta (2nd local contact)
Wolfgang Luberstetter (project engineer)

Publications:

H. Thoma, H. Deng, G. Roth, V. Hutanu, “Setup for polarized neutron diffraction using a high-Tc superconducting magnet on the instrument POLI at MLZ and its applications”, J. Phys.: Conf. Ser. 1316, 012016 (2019), DOI: 10.1088/1742-6596/1316/1/012016.

H. Thoma, W. Luberstetter, J. Peters & V. Hutanu, “Polarised neutron diffraction using novel high-Tc superconducting magnet on single crystal diffractometer POLI at MLZ”, J. Appl. Cryst. 51, 17-26 (2018), DOI: 10.1107/S160057671800078X.

V. Hutanu, W. Luberstetter, E. Bourgeat-Lami, M. Meven, A. Sazonov, A. Steffen, G. Heger, G. Roth, and E. Lelièvre-Berna, “Implementation of a new Cryopad on the diffractometer POLI at MLZ”, Review of Scientific Instruments 87, 105108 (2016), DOI: 10.1063/1.4963697.

V. Hutanu “POLI: Polarised hot neutron diffractometer”, Journal of large-scale research facilities, 1 (2015) A16. DOI: 10.17815/jlsrf-1-22.

  JCNS Copyright: © JCNS

Funding:

Jülich Centre for Neutron Science/Forschungszentrum Jülich

  JARA Copyright: © JARA

Jülich Aachen Research Alliance