The electron paramagnetic resonance spectra of Fe3+ ions, in single crystals which had been prepared by using the flux method, were investigated at room temperature by using a Q-band spectrometer. On the basis of the angular dependence of the electron paramagnetic resonance spectra, two Fe3+ centers which were denoted as C1 and C2 were identified. Here, for the first time, 2 groups of 4 magnetically inequivalent Fe3+ sites - each belonging to the C1 and C2 centers - were fully identified. Two sets of triclinic spin-Hamiltonian parameters were determined which simultaneously fitted the electron paramagnetic resonance data for the 4 sites belonging to the C1 and C2 centers. The directional cosines of the principal axes of the g-tensor, as well as the second-order zero-field splitting tensors of C1 and C2 were found to be consistent with the crystallographic point group, mm2, of the present material.

S.W.Ahn, S.H.Choh, B.C.Choi: Journal of Physics - Condensed Matter, 1995, 7[49], 9615-23