% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@PHDTHESIS{Mller:866248,
      author       = {Müller, Gideon Philipp},
      title        = {{A}dvanced methods for atomic scale spin simulations and
                      application to localized magnetic states},
      volume       = {205},
      school       = {RWTH Aachen},
      type         = {Dr.},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2019-05414},
      isbn         = {978-3-95806-432-4},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {XX, 194 S.},
      year         = {2019},
      note         = {RWTH Aachen, Diss., 2019},
      abstract     = {An active field of research in magnetism today involves
                      studies of solitons – localised magnetic textures
                      possessing particle-like properties. They are considered
                      promising for various applications but are also intriguing
                      from a fundamental point of view. Most of the effects
                      related to magnetic solitons, including in particular
                      skyrmions, can be described in classical spin-lattice
                      models. In this context, effective tools for materials and
                      device design are needed in order to calculate properties,
                      such as thermal stability, lifetime, critical velocity,
                      characteristic dynamical modes and much more. This thesis is
                      devoted to the development of new methodology and the
                      implementation and verification of a new software framework
                      for the simulation of atomistic spin systems. Going beyond
                      the widely known approaches of Monte Carlo and
                      Landau-Lifshitz- Gilbert (LLG) dynamics, this thesis
                      describes the recently developed geodesic nudged elastic
                      band (GNEB) method and harmonic transition state theory in a
                      consistent mathematical framework. The minimum mode
                      following (MMF) method, which can be used to seek out first
                      order saddle points in the energy landscape, is formulated
                      for magnetic systems. Such saddle point searches are an
                      essential part in identifying possible transition processes
                      between magnetic configurations and therefore in estimating
                      the rates of transitions between magnetic states, which
                      determine the states’ lifetimes. Using the MMF method, a
                      mitosis-like skyrmion duplication – or inversely a merger
                      – transition was found and could be reproduced in LLG
                      dynamics simulations using an external magnetic field pulse.
                      The entire set of methods discussed in this thesis has been
                      implemented into a novel, open source software framework.
                      Using scripting and graphical user interfaces, including
                      powerful real-time visualisation features, the methods can
                      now be used easily in conjunction with and complementary to
                      one another. The implementation, including high performance
                      parallelisation schemes, is described and a key set of its
                      features are demonstrated. The software framework is applied
                      to a variety of challenging problems in twoand
                      three-dimensional systems. In two dimensions, complex
                      higher-order skyrmionic textures are studied using the GNEB
                      method and mitosis-like transitions identified.
                      Three-dimensional systems are shown to host a large variety
                      of complex spin textures, including a novel
                      three-dimensionally localised state – the magnetic
                      globule. This state is composed of two coupled
                      quasi-monopoles, also known as Bloch points, and may form
                      stable spin textures in a wide range of parameters and in
                      various situations. The software framework presented here
                      brings simulations of atomic scale magnetic systems to a
                      higher level and represents a significant step in the
                      modernisation of computational tools in magnetism. It brings
                      benefits in productivity and ease of use and improves
                      accessibility of recent and novel methodology.},
      cin          = {PGI-1 / IAS-1 / JARA-FIT / JARA-HPC},
      cid          = {I:(DE-Juel1)PGI-1-20110106 / I:(DE-Juel1)IAS-1-20090406 /
                      $I:(DE-82)080009_20140620$ / $I:(DE-82)080012_20140620$},
      pnm          = {142 - Controlling Spin-Based Phenomena (POF3-142) / 143 -
                      Controlling Configuration-Based Phenomena (POF3-143)},
      pid          = {G:(DE-HGF)POF3-142 / G:(DE-HGF)POF3-143},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      url          = {https://juser.fz-juelich.de/record/866248},
}