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@INPROCEEDINGS{Thoma:897121,
      author       = {Thoma, Henrik and Hutanu, Vladimir and Angst, Manuel and
                      Roth, Georg},
      title        = {{A}bsolute sign of the {D}zyaloshinskii-{M}oriya
                      interaction in weak ferromagnets disclosed by polarized
                      neutron diffraction},
      reportid     = {FZJ-2021-03619},
      year         = {2021},
      abstract     = {Magnetic interactions are the fundamental components for
                      the fascinating variety of complex magnetic structures and
                      properties found in many functional materials. Identifying,
                      understanding, and finally predicting these interactions is
                      an essential step towards their utilization in novel
                      devices. One of these basic interactions is the
                      Dzyaloshinskii-Moriya interaction (DMI) – an antisymmetric
                      exchange coupling favouring a perpendicular arrangement of
                      magnetic moments, and thus a canting in otherwise collinear
                      structures [1,2]. The DMI, originally introduced in the late
                      1950s to explain ‘weak ferromagnets’ (not perfectly
                      collinear antiferromagnets), regained the interest in
                      current condensed matter research as it was found to be the
                      driving force to stabilize various novel topological
                      noncollinear magnetic structures, such as spin spirals [3],
                      magnetic skyrmions [4], magnetic soliton lattices [5] and
                      others. In particular for spintronic applications, the DMI
                      shows promising characteristics towards the development of
                      next-generation devices [6]. Although the magnitude of the
                      DMI-induced canting is usually small, the direction can have
                      a fundamental impact on the spin chirality and the resulting
                      magnetic and multiferroic properties [7]. Here, we present
                      polarized neutron diffraction (PND) as an efficient
                      technique for the determination of the absolute direction of
                      the DMI in weak ferromagnetic materials, as recently
                      established by us [8]. We provide the basic formalism for a
                      symmetry analysis of the DMI in crystal structures and show
                      how to relate the measured PND data with the absolute DMI
                      direction. We exemplify this approach in weak ferromagnetic
                      MnCO3 and identify the magnetic moment configurations for a
                      positive or negative sign of the DMI with an applied
                      magnetic field. Using PND [9], we can distinguish even from
                      the measurement of a single suitable Bragg reflection
                      between the two configurations and unambiguously reveal a
                      negative DMI sign in MnCO3. This is in agreement with
                      previous results obtained by resonant magnetic X-ray
                      scattering and thus, validates the method [10]. We
                      demonstrate the generality of our method by providing
                      further examples of topical magnetic materials with
                      different symmetries and support our findings with ab-initio
                      calculations, which reproduce the experimental results. [1]
                      V. E. Dzyaloshinskii, Sov. Phys. - JETP 5(6), 1259 (1957)[2]
                      T. Moriya, Phys. Rev. 120(1), 91 (1960),[3] M. Bode et al.,
                      Nature 447, 190 (2007),[4] S. Heinze et al., Nat. Phys. 7,
                      713 (2011),[5] Y. Togawa et al., Phys. Rev. Lett. 108,
                      107202 (2012),[6] S. S. P. Parkin et al., Science 320, 190
                      (2008),[7] J. Cho et al., J. Phys. D: Appl. Phys. 50, 425004
                      (2017),[8] H. Thoma et al., Phys. Rev. X 11, 011060
                      (2021),[9] H. Thoma et al., J. Appl. Crystallogr. 51, 17
                      (2018),[10] V. E. Dmitrienko et al., Nat. Phys. 10, 202
                      (2014)},
      month         = {Aug},
      date          = {2021-08-14},
      organization  = {XXV General Assembly and Congress of
                       the International Union of
                       Crystallography, Prague (Czech
                       Republic), 14 Aug 2021 - 22 Aug 2021},
      subtyp        = {After Call},
      cin          = {JCNS-FRM-II / JARA-FIT / JCNS-2 / JCNS-4 / MLZ},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
                      $I:(DE-82)080009_20140620$ / I:(DE-Juel1)JCNS-2-20110106 /
                      I:(DE-Juel1)JCNS-4-20201012 / I:(DE-588b)4597118-3},
      pnm          = {6G4 - Jülich Centre for Neutron Research (JCNS) (FZJ)
                      (POF4-6G4) / 632 - Materials – Quantum, Complex and
                      Functional Materials (POF4-632)},
      pid          = {G:(DE-HGF)POF4-6G4 / G:(DE-HGF)POF4-632},
      experiment   = {EXP:(DE-MLZ)POLI-HEIDI-20140101},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/897121},
}