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@ARTICLE{Weigel:584521,
      author       = {Weigel, Tina and Richter, Carsten and Nentwich, Melanie and
                      Garbe, Valentin and Mehner, Erik and Bouchnoir, Laurence and
                      Novikov, Dmitri and Meyer, Dirk C. and Zschornak, Matthias},
      title        = {{P}icometer atomic displacements behind ferroelectricity in
                      the commensurate low-temperature phase in multiferroic
                      {YM}n$_2${O}$_5$},
      journal      = {Physical review / B},
      volume       = {109},
      number       = {5},
      issn         = {2469-9950},
      address      = {Woodbury, NY},
      publisher    = {Inst.},
      reportid     = {PUBDB-2023-03136},
      pages        = {054101},
      year         = {2024},
      abstract     = {Multiferroics are rare materials that exhibit an
                      interaction of ferroelectricity and magnetism. One such
                      multiferroic material is the Mn-based mullite YMn$_2$O$_5$.
                      YMn$_2$O$_5$ undergoes several low-temperature phases, and
                      the origin of ferroelectricity in the commensurate phase
                      remains open. Changes in the Mn spin configuration are
                      believed to be the main driving force, which can be induced
                      by magnetostriction caused by symmetric exchange, the
                      antisymmetric inverse Dzyaloshinskii-Moriya interaction, or
                      a combination of both. These mechanisms are accompanied by
                      specific displacements of ions in the structure. The space
                      group Pbam(55) of the paraelectric phase does not allow
                      polar displacements. Moreover, conventional structure
                      analysis has been unsuccessful in refining the charge
                      structure in a lower symmetric phase due to its limited
                      sensitivity in resolving the expected positional
                      displacements. To shed light on this controversial
                      discussion, our goal was to resolve potential ionic
                      displacements within a polar space group by employing the
                      new resonantly suppressed diffraction method, which is
                      highly sensitive to minuscule structural changes in the
                      (sub)picometer range. In this paper, we present the first
                      refined structure model of the commensurate phase in
                      YMn$_2$O$_5$ using the lower symmetric space group Pb2$_1$m,
                      allowing polarization in the b direction. We observed a
                      significant displacement of the Mn ions and the partial
                      structure of oxygen, resulting in a calculated spontaneous
                      polarization P$_S$=(1.3±0.4)mCm$^{−2}$, which is in good
                      agreement with our measured value
                      P$_S$=(0.88±0.06)mCm$^{−2}$. Importantly, we confirm that
                      PS predominantly arises from an ionic contribution induced
                      by magnetostriction. These results hold great interest not
                      only for all multiferroic Mn-based mullites, but also for
                      other multiferroic materials where ferroelectricity arises
                      from their magnetic order. Furthermore, a precise
                      understanding of the ionic movement induced by magnetism
                      will aid in the material tuning process to enhance or create
                      multiferroic properties.},
      cin          = {DOOR ; HAS-User / FS-PETRA-D / IT / FS-PET-D},
      ddc          = {530},
      cid          = {I:(DE-H253)HAS-User-20120731 /
                      I:(DE-H253)FS-PETRA-D-20210408 / I:(DE-H253)IT-20120731 /
                      I:(DE-H253)FS-PET-D-20190712},
      pnm          = {631 - Matter – Dynamics, Mechanisms and Control
                      (POF4-631) / 6G3 - PETRA III (DESY) (POF4-6G3) / DFG project
                      324641898 - Resonante Röntgendiffraktion unter optimierter
                      destruktiver Interferenz zur hochsensitiven Bestimmung
                      phasenaufgelöster lagespezifischer Atomverrückungen in
                      kristallinen Materialien (324641898) / DFG project 409743569
                      - Kontrollierte Einstellung der Atomstruktur in
                      Funktionsmaterialien durch akustische Wellen und elektrische
                      Felder (409743569) / DFG project 397252409 - Compute Cluster
                      zur Zentralisierung der Rechenbedarfe (397252409) / EURIZON
                      - European network for developing new horizons for RIs
                      (871072)},
      pid          = {G:(DE-HGF)POF4-631 / G:(DE-HGF)POF4-6G3 /
                      G:(GEPRIS)324641898 / G:(GEPRIS)409743569 /
                      G:(GEPRIS)397252409 / G:(EU-Grant)871072},
      experiment   = {EXP:(DE-H253)P-P23-20150101},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:001198608300002},
      doi          = {10.1103/PhysRevB.109.054101},
      url          = {https://bib-pubdb1.desy.de/record/584521},
}