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@ARTICLE{Zhang:902637,
      author       = {Zhang, Guoren and Pavarini, Eva},
      title        = {{M}agnetic superexchange couplings in {S}r 2 {I}r{O} 4},
      journal      = {Physical review / B},
      volume       = {104},
      number       = {12},
      issn         = {1098-0121},
      address      = {Woodbury, NY},
      publisher    = {Inst.},
      reportid     = {FZJ-2021-04432},
      pages        = {125116},
      year         = {2021},
      abstract     = {We investigate the magnetic couplings in Sr2IrO4 in the
                      Mott-insulating picture, combining density-functional
                      theory, dynamical mean-field theory, and many-body
                      perturbation theory. We first determine the form of the
                      jeff=1/2 pseudospin via the local-density-approximation +
                      dynamical mean-field theory approach. Next we study the
                      magnetic interactions in the strong-to-intermediate coupling
                      regime. To this end, we calculate the superexchange
                      pseudospin tensors Γ1, Γ2, and Γ3 up to fourth order and
                      analyze their dependence on the screened Coulomb interaction
                      integrals U and J. We show that, due to term cancellations,
                      the experimental nearest-neighbor coupling Γ1 is reasonably
                      well reproduced for a whole range of realistic (U,J) values.
                      We show that increasing the Hund's rule coupling J (within
                      the window of realistic values) can lead to large
                      fourth-order contributions, which could explain the
                      ferromagnetic next-nearest-neighbor coupling Γ2 extracted
                      from the spin-wave dispersion. This regime is characterized
                      by a sizable ring exchange K. For (U,J) values that yield a
                      Mott insulator with a half-filled jeff=1/2 state, however,
                      fourth-order terms remain minor even if the gap is small.
                      For no realistic parameters, we find a sizable
                      next-next-nearest-neighbor coupling Γ3∼|Γ2|. Possible
                      implications are discussed.},
      cin          = {IAS-3},
      ddc          = {530},
      cid          = {I:(DE-Juel1)IAS-3-20090406},
      pnm          = {5221 - Advanced Solid-State Qubits and Qubit Systems
                      (POF4-522)},
      pid          = {G:(DE-HGF)POF4-5221},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000704419000001},
      doi          = {10.1103/PhysRevB.104.125116},
      url          = {https://juser.fz-juelich.de/record/902637},
}