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@PHDTHESIS{Abuawwad:1039804,
      author       = {Abuawwad, Nihad},
      title        = {{A}b initio investigation of topological magnetism in
                      two-dimensional van der {W}aals heterostructures},
      volume       = {291},
      school       = {Duisburg-Essen},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2025-01804},
      isbn         = {978-3-95806-808-7},
      series       = {Schriften des Forschungszentrums Jülich Reihe
                      Schlüsseltechnologien / Key Technologies},
      pages        = {xviii, 135},
      year         = {2025},
      note         = {Dissertation, Duisburg-Essen, 2024},
      abstract     = {Magnetism in two-dimensional (2D) van der Walls (vdW)
                      materials is a rapidly evolving field in condensed matter
                      physics and materials science, marked by intriguing
                      discoveries and potential applications. Unlike traditional
                      three-dimensional materials, 2D vdW materials are
                      characterized by their ultra-thin, often single-layer,
                      structure leading to unique magnetic properties triggered by
                      proximity-effects, which are facilitated by the underlying
                      vdW gap. Such properties are not only fundamental for
                      understanding the physics of low-dimensional systems but
                      also hold immense promise for the development of advanced
                      technologies in data storage, spintronics, and quantum
                      computing. Building on the foundational understanding of
                      magnetism in 2D materials, this thesis dives deeper into the
                      specific case of CrTe2 and CrSBr. Based on a multiscale
                      modelling approach that combines first-principles
                      calculations and a Heisenberg model supplied with ab-initio
                      parameters, we report a strong magnetoelastic coupling in a
                      free-standing monolayer of CrTe2. We demonstrate that
                      different crystal structures of a single CrTe2 give rise to
                      non-collinear magnetism through magnetic frustration and the
                      emergence of the Dzyaloshinskii-Moriya interaction (DMI).
                      Utilizing atomistic spin relaxation, we perform a detailed
                      investigation of the complex magnetic properties pertaining
                      to this 2D material impacted by the presence of various
                      types of structural distortions akin to charge density
                      waves. Also, we demonstrate that interfacing a CrTe2 layer
                      with various Te-based layers enables the control of the
                      magnetic exchange and Dzyaloshinskii-Moriya interactions as
                      well as the magnetic anisotropy energy of the whole
                      heterobilayer, and thereby the emergence of topological
                      magnetic phases such as skyrmions and antiferromagnetic
                      N´eel merons. The latter are novel particles in the world
                      of topological magnetism since they arise in a frustrated
                      N´eel magnetic environment and manifest as multiples of
                      intertwined hexamer-textures. Our findings pave a promising
                      road for proximity-induced engineering of both ferromagnetic
                      and long-sought antiferromagnetic chiral objects in the very
                      same 2D material, which is appealing for new information
                      technology devices employing quantum materials. Moreover, we
                      demonstrate the all-electric switching of the topological
                      nature of individual magnetic objects emerging in 2D vdW
                      heterobilayers. We show that an external electric field
                      modifies the vdW gap between CrTe2 and (Rh, Ti)Te2 layers
                      and alters the underlying magnetic interactions. This
                      enables switching between ferromagnetic skyrmions and meron
                      pairs in the CrTe2/RhTe2 heterobilayer while it enhances the
                      stability of frustrated antiferromagnetic merons in the
                      CrTe2/TiTe2 heterobilayer. We envision that the electrical
                      engineering of distinct topological magnetic solitons in a
                      single device could pave the way for novel energy-efficient
                      mechanisms to store and transmit information with
                      applications in spintronics. Finally, via machine learning
                      concepts we integrated linear spin wave theory (LSWT) with
                      activelearning sampling to develop a Kalman Filter
                      Adversarial Bayesian Optimization (KFABO) algorithm. This
                      algorithm excels at managing highly noisy experimental
                      spectra of 2D bulk CrSBr, aiming to map the experimentally
                      extracted magnon spectrum with minimal sampling points and
                      iterations. Additionally, the KFABO algorithm is designed to
                      accurately extract magnetic parameters from inelastic
                      neutron scattering data, significantly enhancing the
                      efficiency and accuracy of experimental measurements.},
      cin          = {PGI-1},
      cid          = {I:(DE-Juel1)PGI-1-20110106},
      pnm          = {5211 - Topological Matter (POF4-521)},
      pid          = {G:(DE-HGF)POF4-5211},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      doi          = {10.34734/FZJ-2025-01804},
      url          = {https://juser.fz-juelich.de/record/1039804},
}