Investigations of ESR superhyperfine structure for the cubic Gd3+ center in CaF2, SrF2, and BaF2

Abstract

A partially resolved superhyperfine structure has been observed in the ESR spectra of the cubic Gd3+ center in CaF2, SrF2, and BaF2. This superhyperfine structure has been satisfactorily analyzed in terms of the interaction of the Gd3+ ion with its eight nearest-neighbor 19F nuclear spins associated with the cubic Gd3+ center. The values of the fluorine superhyperfine interaction constants T∥ and T⊥ obtained by this analysis are (in units of MHz): T∥=7.5±0.2, T⊥=−6.7± 0.2 for SrF2; T∥=8.0±0.3, T⊥=−5.9± 0.3 for BaF2; and T∥=8.1±0.2, T⊥=−7.1± 0.2 for CaF2 (which agree with those determined previously by ENDOR).