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Dynamical Nature of Superexchange Interaction in Y 3 Fe 5 O 12 Studied by Neutron Spectroscopy
Author(s) -
Ligenza S.
Publication year - 1985
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221310109
Subject(s) - superexchange , quadrupole , electric field gradient , condensed matter physics , chemistry , neutron , inelastic neutron scattering , ion , magnetic moment , neutron scattering , spectral line , physics , atomic physics , antiferromagnetism , nuclear physics , organic chemistry , astronomy
Abstract Inelastic neutron scattering is used to investigate spin interactions in polycrystalline Y 3 Fe 5 O 12 . Neutron spectra due to local spin interaction are observed and interpreted by the 6 S 5/2 ‐term splitting of Fe 3+ ions located in octahedral (a)‐sites and tetrahedral (d)‐sites of the garnet structure. The observed neutron spectra are analyzed using a phenomenological spin Hamiltonian assuming combined interaction of magnetic and quadrupole electric moments of the 3d 5 electron shell with a static magnetic molecular field and a static electric field gradient, respectively. The neutron energy peaks connected with various magnetic coordination numbers at (a)‐sites and (d)‐sites are obtained. This phenomenon is interpreted as due to the dynamical nature of superexchange interaction of Fe 3+ ions in YIG. The dynamical interactions bring about fluctuations of the magnetic moments with a relaxation rate between 10 −8 s > τ m > 10 −13 s. The quadrupole and superexchange interaction parameters are determined to D = −0.508 meV and E s = 3.00 meV, respectively. The effect of lowering of magnetic moments of Fe 3+ ions situated on (a)‐ and (d)‐sites is discussed.