Multiboson spin-wave theory for Ba2CoGe2O 7: A spin-3/2 easy-plane Néel antiferromagnet with strong single-ion anisotropy

Judit Romhányi, Karlo Penc

Research output: Article

19 Citations (Scopus)


We consider the square-lattice antiferromagnetic Heisenberg Hamiltonian extended with a single-ion axial anisotropy term as a minimal model for the multiferroic Ba2CoGe2O7. Developing a multiboson spin-wave theory, we investigate the dispersion of the spin excitations in this spin-3/2 system. As a consequence of a strong single-ion anisotropy, a stretching (longitudinal) spin mode appears in the spectrum. The inelastic neutron scattering spectra of Zheludev are successfully reproduced by the low energy modes in the multiboson spin-wave theory, and we anticipate the appearance of the spin stretching modes at 4 meV that can be identified using the calculated dynamical spin structure factors. We expect the appearance of spin stretching modes for any S 1/2 compound where the single-ion anisotropy is significant.

Original languageEnglish
Article number174428
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number17
Publication statusPublished - nov. 28 2012

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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