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@PHDTHESIS{Skaugen:208324,
      author       = {Skaugen, Arvid},
      othercontributors = {Roehlsberger, Ralf and Rübhausen, Michael},
      title        = {{E}xchange {I}nteractions and {I}nduced ${E}u^{3+}$
                      {M}agnetic {O}rder in ${RM}n{O}_{3}$ {I}nvestigated {U}sing
                      {R}esonant {X}-ray {D}iffraction},
      issn         = {1435-8085},
      school       = {Universität Hamburg},
      type         = {Dissertation},
      publisher    = {Verlag Deutsches Elektronen-Synchrotron},
      reportid     = {PUBDB-2015-01676, DESY-THESIS-2015-011},
      series       = {DESY-THESIS},
      pages        = {137},
      year         = {2015},
      note         = {Dissertation, Universität Hamburg, 2015},
      abstract     = {The so-called multiferroics, materials that concomitantly
                      exhibit more than one ferroic order, have in recent years
                      attracted much attention owing totheir possible applications
                      in high density data storage, high sensitivity ac magnetic
                      field sensors and novel spintronic devices. In particular,
                      multifer-roics with strong magnetoelectric coupling are more
                      attractive. Among such multiferroics, an interesting special
                      class is the orthorhombic manganiteswith perovskite
                      structure. In these compounds, frustration serves to
                      destabilize ordinary ferromagnetic or antiferromagnetic
                      ordering, giving rise to richphase diagrams due to several
                      competing magnetic interactions. Interactions between strong
                      rare earth magnetic moments and weaker transition
                      metalmoments add another level of complexity, as well as
                      interest. The current dissertation presents results obtained
                      investigating the mag-netic structure responsible for
                      ferroelectricity in a few selected multiferroic compounds,
                      using x-ray resonant magnetic scattering (XRMS). In
                      particular,single crystals of Eu1−xYxMnO3 have been
                      studied at low temperatures and in high magnetic fields.
                      This series of compounds is similar in structure tothe
                      heavily studied RMnO3 (R=Tb,Gd,Dy), only without rare earth
                      magnetism. The novel technique of full polarization analysis
                      has been used todetermine the complicated cycloidal Mn
                      magnetic ordering, and additional components due to the
                      Dzyaloshinskii-Moriya interactions have been iden-tified. In
                      the compound Eu0.8Y0.2MnO3, two coexisting multiferroic
                      phases were observed, and a magnetoelectric coupling between
                      the two was established. Moreover, magnetic order of the
                      formally non-magnetic rare earth ion Eu3+ was observed in
                      the same compound. It has been concluded toresult from a Van
                      Vleck type excitation of the J = 0 ground state due to the
                      symmetry-breaking internal exchange field from the Mn
                      magnetic moments.In addition, this dissertation reports on
                      high field investigations of the complex low-temperature
                      phases of GdMnO3 as well as high energy non-resonant
                      scattering studies of TbMnO3. In the case of TbMnO3, the
                      simple high energy magnetic cross section allowed for direct
                      determination of spincomponents in the ferroelectric phase.
                      In the case of GdMnO3, the first high field XRMS
                      investigation below the Gd ordering temperature was
                      performed, revealing an important role of the symmetric
                      exchange interaction between the Gd and Mn subsystems for
                      stabilizing ferroelectricity in the compound.},
      keywords     = {Dissertation (GND)},
      cin          = {FS-PE},
      cid          = {I:(DE-H253)FS-PE-20120731},
      pnm          = {6212 - Quantum Condensed Matter: Magnetism,
                      Superconductivity (POF3-621) / 6G3 - PETRA III (POF3-622) /
                      PHGS, VH-GS-500 - PIER Helmholtz Graduate School
                      $(2015_IFV-VH-GS-500)$},
      pid          = {G:(DE-HGF)POF3-6212 / G:(DE-HGF)POF3-6G3 /
                      $G:(DE-HGF)2015_IFV-VH-GS-500$},
      experiment   = {EXP:(DE-H253)P-P09-20150101 / EXP:(DE-H253)P-P07-20150101},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.3204/DESY-THESIS-2015-011},
      url          = {https://bib-pubdb1.desy.de/record/208324},
}