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Magneto‐electric splitting of the crystal field Γ 2 ‐level of Cr 3+ ions in MgCr 2 O 4 studied by neutron spectroscopy
Author(s) -
Ligenza S.,
PtasiewiczBąk H.
Publication year - 1978
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.2220900135
Subject(s) - neutron diffraction , ion , neutron , magnetic moment , octahedron , atomic physics , crystallography , chemistry , crystal structure , physics , condensed matter physics , organic chemistry , quantum mechanics
Neutron spectroscopic studies are made on polycrystalline MgCr 2 O 4 spinel at temperatures between 5 and 293 K. Neutron spectra connected with local spin interaction are observed and interpreted basing on the splitting of Γ 2 ‐level belonging to the 4 F 3/2 ‐term of Cr 3+ ions situated at octahedral B‐sites. The fourfold Γ 2 ‐level splitting and the neutron excited transitions are analysed in terms of a spin‐Hamiltonian assuming a magneto‐electric interaction of the 3d 3 electron shells. In spectroscopic measurements the set of peaks connected with two kinds of B‐sites are observed. According to neutron diffraction measurements the local magnetic‐molecular field at those sites makes the angles θ x = 90° (B(x)) and θ v = 35° (B(v)) with a trigonal axis of electric field. From spectral analysis the energies of Γ 2 ‐level splitting are determined for Cr 3+ ions at B(x) and B(v) sites, and the respective interaction parameters are found. Basing on interaction parameters the magnetic moments of Cr 3+ at B(x) and B(v) sites are calculated to be μ(x) = (2.64 ± 0.02) and μ(v) = (1.80 ± 0.02) BM, respectively. From neutron diffraction measurements the magnetic moments at B(x) and B(v) sites are found to be μ d (x) = (2.70 ± 0.10) and μ d (v) = (1.83 ± 0.10) BM, in good agreement with moments calculated from spectroscopic data.