Browsing by Author "Wang, Chong"

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    Longitudinal Spin Excitations and Magnetic Anisotropy in Antiferromagnetically Ordered BaFe2As2
    (American Physical Society, 2013) Wang, Chong; Zhang, Rui; Wang, Fa; Luo, Huiqian; Regnault, L.P.; Dai, Pengcheng; Li, Yuan
    We report on a spin-polarized inelastic neutron-scattering study of spin waves in the antiferromagnetically ordered state of BaFe2As2. Three distinct excitation components are identified, with spins fluctuating along the c axis, perpendicular to the ordering direction in the ab plane and parallel to the ordering direction. While the first two “transverse” components can be described by a linear spin-wave theory with magnetic anisotropy and interlayer coupling, the third “longitudinal” component is generically incompatible with the local-moment picture. It points toward a contribution of itinerant electrons to the magnetism that is already in the parent compound of this family of Fe-based superconductors.
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    Spin waves and Dirac magnons in a honeycomb-lattice zigzag antiferromagnet BaNi2(AsO4)2
    (American Physical Society, 2021) Gao, Bin; Chen, Tong; Wang, Chong; Chen, Lebing; Zhong, Ruidan; Abernathy, Douglas L.; Xiao, Di; Dai, Pengcheng
    The topological properties of massive and massless fermionic quasiparticles have been intensively investigated over the past decade in topological materials without magnetism. Recently, the bosonic analogs of such quasiparticles arising from spin waves have been reported in a two-dimensional (2D) honeycomb-lattice ferromagnet/antiferromagnet and a 3D antiferromagnet. Here, we use time-of-flight inelastic neutron scattering to study spin waves of the S=1 honeycomb-lattice antiferromagnet BaNi2(AsO4)2, which has a zigzag antiferromagnetic (AFM) ground state identical to that of the Kitaev quantum spin liquid candidate α−RuCl3. We determine the magnetic exchange interactions in the zigzag AFM ordered phase, and show that spin waves in BaNi2(AsO4)2 have symmetry-protected Dirac points inside the Brillouin zone boundary. These results provide a microscopic understanding of the zigzag AFM order and associated Dirac magnons in honeycomb-lattice magnets, and are also important for establishing the magnetic interactions in Kitaev quantum spin liquid candidates.