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@PHDTHESIS{Granton:828400,
      author       = {Géranton, Guillaume},
      title        = {{I}ntrinsic and extrinsic spin-orbit torques from first
                      principles},
      volume       = {141},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2017-02361},
      isbn         = {978-3-95806-213-9},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {122 S.},
      year         = {2017},
      note         = {RWTH Aachen, Diss., 2017},
      abstract     = {This thesis attempts to shed light on the microscopic
                      mechanisms underlying the current-induced magnetic torques
                      in ferromagnetic heterostructures. We have developed first
                      principles methods aiming at the accurate and efficient
                      calculation of the so-called spin-orbit torques (SOTs) in
                      magnetic thin films. The emphasis of this work is on the
                      impurity-driven extrinsic SOTs. The main part of this thesis
                      is dedicated to the development of a formalism for the
                      calculation of the SOTs within the Korringa-Kohn-Rostoker
                      (KKR) method. The impurity-induced transitions rates are
                      obtained from first principles and their effecton transport
                      properties is treated within the Boltzmann formalism. The
                      developed formalism provides a mean to compute the SOTs
                      beyond the conventional constant relaxation time
                      approximation. We first apply our formalism to the
                      investigation of FePt/Pt and Co/Cu bilayers in the presence
                      of defects and impurities. Our results hint at a crucial
                      dependence of the torque on the type of disorder present in
                      the films, which we explain by a complex interplay of
                      several competing Fermi surface contributions to the SOT.
                      Astonishingly, specific defect distributions or doping
                      elements lead respectively to an increase or a sign change
                      of the torque, which can not be explained on the basis of
                      simple models. We also compute the intrinsic SOT induced by
                      electrical and thermal currents within the full potential
                      linearized augmented plane-wave method. Motivated by recent
                      experimental works, we then investigate the microscopic
                      origin of the SOT in a Ag$_{2}$Bi-terminated Ag film grown
                      on ferromagnetic Fe(110). We find that the torque in that
                      system can not be explained solely by the spin-orbit
                      coupling in the Ag$_{2}$Bi alloy, and instead results from
                      the spin-orbit coupling in all regions of the film. Finally,
                      we predict a large SOT in Fe/Ge bilayers and suggest that
                      semiconductor substrates might be a promising alternative to
                      heavy metals for the development of SOT-based magnetic
                      random access memories. We show the strong dependence of the
                      SOT on the stacking direction, thereby providing important
                      guidelines for future experimental works. We also compute
                      the sublattice-resolved SOTs in an antiferromagnetic Fe/Ge
                      thin film and find a large anisotropy of the torkance
                      tensor.},
      cin          = {IAS-1 / PGI-1},
      cid          = {I:(DE-Juel1)IAS-1-20090406 / I:(DE-Juel1)PGI-1-20110106},
      pnm          = {899 - ohne Topic (POF3-899)},
      pid          = {G:(DE-HGF)POF3-899},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/828400},
}