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@INPROCEEDINGS{Thoma:859470,
      author       = {Thoma, Henrik and Hutanu, Vladimir and Deng, Hao and Roth,
                      Georg},
      title        = {{S}etup for polarized neutron diffraction using a novel
                      high-{T}c superconducting magnet at instrument {POLI} at
                      {MLZ}},
      reportid     = {FZJ-2019-00326},
      year         = {2018},
      abstract     = {Polarized neutron diffraction (PND) is a powerful method to
                      investigate magnetic structures. PND can be used for very
                      precise magnetization measurements even for weak magnetic
                      contributions. It allows the high-quality determination of
                      magnetic form factors, to untangle complex (e.g. chiral)
                      magnetic structures, and to follow the movement of magnetic
                      domains. In this technique, spin flip measurements are
                      carried out on a sample, located in a strong magnetic field.
                      Optionally, the scattered beam can be analyzed to perform a
                      polarization analysis along the given field direction at the
                      sample.A new PND setup has been developed for the hot
                      neutron single crystal diffractometer POLI [1] at MLZ. This
                      setup consists of a ³He spin filter cell [2] for
                      polarization, a Mezei flipper optimized for short-wavelength
                      neutrons, and a new high Tc superconducting magnet producing
                      fields up to 2.2 T. Because the magnet provides a symmetric
                      field configuration, a dedicated guide field system was
                      designed in order to avoid neutron depolarization in the
                      zero-field node. The polarization transport efficiency of
                      the whole setup was numerically simulated and optimized
                      [3].By using either a Heusler crystal at the sample position
                      or a second spin filter cell as analyzer, the polarization
                      losses in the setup were confirmed to be below $2\%$ over
                      the total field range of the magnet. With the ³He cell as
                      polarizer, a beam polarization over $90\%$ at a wavelength
                      as short as 0.7 Å is reliably reachable. The stray fields
                      of the magnet did not affect the relaxation time T1 of the
                      ³He spin filter polarizer. Typical T1 values above 100 h
                      are measured. . First experiments with antiferromagnetic and
                      paramagnetic samples using the new setup have been
                      successfully performed. Using the CCSL software,
                      reconstruction of the field induced spin density
                      distribution in the weak ferromagnet MnCO3 was performed in
                      the paramagnetic state and compared to the literature data.
                      Our results shows the high performance and good resolution
                      of the setup.[1] V. Hutanu, Heinz Maier-Leibnitz Zentrum,
                      Journal of large-scale research facilities, 1, A16 (2015)[2]
                      V. Hutanu, M. Meven, S. Masalovich et al., J. Phys.: Conf.
                      Ser., 294, 012012 (2011)[3] H. Thoma, W. Luberstetter, J.
                      Peters, and V. Hutanu, J. Appl. Cryst. 51, 17-26 (2018)},
      month         = {Jul},
      date          = {2018-07-03},
      organization  = {Polarised Neutrons for
                       Condensed-Matter Investigations 2018,
                       Abingdon (England), 3 Jul 2018 - 6 Jul
                       2018},
      subtyp        = {After Call},
      cin          = {JCNS-FRM-II / JCNS-2 / JARA-FIT},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
                      I:(DE-Juel1)JCNS-2-20110106 / $I:(DE-82)080009_20140620$},
      pnm          = {524 - Controlling Collective States (POF3-524) / 6212 -
                      Quantum Condensed Matter: Magnetism, Superconductivity
                      (POF3-621) / 6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich
                      Centre for Neutron Research (JCNS) (POF3-623)},
      pid          = {G:(DE-HGF)POF3-524 / G:(DE-HGF)POF3-6212 /
                      G:(DE-HGF)POF3-6G15 / G:(DE-HGF)POF3-6G4},
      experiment   = {EXP:(DE-MLZ)POLI-HEIDI-20140101},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/859470},
}