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@INPROCEEDINGS{Su:1034884,
      author       = {Su, Yixi},
      title        = {{T}opological magnons in van der {W}aals ferromagnets
                      {C}r{XT}e$_3$ ({X} = {S}i, {G}e)},
      reportid     = {FZJ-2025-00007},
      year         = {2024},
      abstract     = {Recently, two-dimensional van der Waals (2D-vdW) honeycomb
                      ferromagnets have emerged as a new platform for topological
                      spin excitations. In this talk, we present a comprehensive
                      inelastic neutron scattering study and theoretical analysis
                      of the spin-wave excitations in 2D-vdW honeycomb
                      ferromagnets CrXTe3 (X = Si, Ge) [1-2]. Our inelastic
                      neutron scattering experiments show clear dispersive
                      magnonic bands and a well-resolved bandgap opening at the
                      high-symmetry band-crossing Dirac K points in the Brillouin
                      zone. Based on the fitting to experimental data within the
                      linear spin wave theory, the observed bandgap opening was
                      ascribed to the antisymmetric exchange Dzyaloshinskii-Moriya
                      interactions (DMI), and a spin Hamiltonian model including
                      the second nearest-neighbor DMI could provide a very good
                      description of the magnonic dispersion in CrXTe3. The size
                      of the topological magnonic gap was found to be strongly
                      dependent on the strength of the DMI that intrinsically
                      originates from spin-orbit coupling in this system.
                      Furthermore, the Chern numbers of the magnonic bands were
                      found to be nonzero, thus indicating that the bandgap
                      opening is indeed topologically nontrivial and corresponding
                      edge states could emerge inside the gap. On the basis of the
                      compelling evidence obtained in our studies, we thus
                      conclude that the exotic topological magnon insulator, which
                      is intrinsically gap tunable, can be ideally realized in the
                      family of 2D vdW honeycomb ferromagnets CrXTe3. We hope that
                      this discovery will stimulate further investigations on
                      potential technological applications in the domain of
                      magnonics and topological spintronics.[1] Fengfeng Zhu, et
                      al., Sci. Adv. 7, eabi7532 (2021)[2] Li-Chuan Zhang, et al.,
                      Phys. Rev. B 103, 134414 (2021)},
      month         = {Jan},
      date          = {2024-01-02},
      organization  = {Towards Functional van der Waals
                       magnets by Unlocking Synergies with
                       Orbitronics, Magnonics, Altermagnetism,
                       and Optics, Physikzentrum, Bad Honnef
                       (Germany), 2 Jan 2024 - 5 Jan 2024},
      subtyp        = {Invited},
      cin          = {JCNS-FRM-II / MLZ},
      cid          = {I:(DE-Juel1)JCNS-FRM-II-20110218 / I:(DE-588b)4597118-3},
      pnm          = {632 - Materials – Quantum, Complex and Functional
                      Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
                      Research (JCNS) (FZJ) (POF4-6G4)},
      pid          = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
      experiment   = {EXP:(DE-MLZ)DNS-20140101 / EXP:(DE-MLZ)PUMA-20140101 /
                      EXP:(DE-Juel1)ILL-IN12-20150421 /
                      EXP:(DE-MLZ)External-20140101},
      typ          = {PUB:(DE-HGF)6},
      url          = {https://juser.fz-juelich.de/record/1034884},
}