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@ARTICLE{Musshoff:872850,
      author       = {Musshoff, Julian and Zhang, Guoren and Koch, Erik and
                      Pavarini, Eva},
      title        = {{L}inear-response description of super-exchange driven
                      orbital-ordering in {K}2{C}u{F}4},
      journal      = {Physical review / B},
      volume       = {100},
      number       = {4},
      issn         = {0163-1829},
      address      = {Woodbury, NY},
      publisher    = {Inst.},
      reportid     = {FZJ-2020-00318},
      pages        = {045116},
      year         = {2019},
      abstract     = {We study the nature of orbital and magnetic order in the
                      layered perovskite K2CuF4, and compare to the case of the
                      infinite-layer system KCuF3. To this end, we augment the
                      local-density approximation + dynamical mean-field theory
                      technique with linear-response functions. We explain orbital
                      and magnetic order, and their evolution with increasing
                      pressure. We show that both the tetragonal (ɛT) and the
                      Jahn-Teller (ɛJT) crystal-field splitting play a key role.
                      We find that surprisingly, unlike in KCuF3,ɛT is comparable
                      to, or even larger than, ɛJT; in addition, ɛT is mostly
                      determined by the layered structure itself and by the
                      compression of the K cage, rather than by the deformations
                      of the CuF6 octahedra. Next, we study the nature of orbital
                      order. We calculate the superexchange transition
                      temperature, finding TKK∼300K, a value close to the one
                      for KCuF3. Thus, in K2CuF4 as in KCuF3,TKK is too small to
                      explain the existence of orbital order up to the melting
                      temperature. We show, however, that in the case of the
                      layered perovskite, an additional superexchange mechanism is
                      at work. It is an orbital Zeeman term, ˆhKK, and it is
                      active also above TKK. We show that due to ˆhKK, phases
                      with different types of ordering can coexist at temperatures
                      below TKK. Similar effects are likely to play a role in
                      other layered correlated systems.},
      cin          = {IAS-3 / JSC / JARA-HPC / NIC},
      ddc          = {530},
      cid          = {I:(DE-Juel1)IAS-3-20090406 / I:(DE-Juel1)JSC-20090406 /
                      $I:(DE-82)080012_20140620$ / I:(DE-Juel1)NIC-20090406},
      pnm          = {144 - Controlling Collective States (POF3-144) / 511 -
                      Computational Science and Mathematical Methods (POF3-511) /
                      Spin-orbital order-disorder transitions in strongly
                      correlated systems $(jiff46_20161101)$},
      pid          = {G:(DE-HGF)POF3-144 / G:(DE-HGF)POF3-511 /
                      $G:(DE-Juel1)jiff46_20161101$},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000475499700003},
      doi          = {10.1103/PhysRevB.100.045116},
      url          = {https://juser.fz-juelich.de/record/872850},
}