ENDOR Study of Cubic Fe³⁺ Centres in KMgF₃

Abstract

Abstract The superhyperfine (shf) interactions of the Fe 3+ impurity ion in KMgF 3 with its nearest neighbour (n.n.) and next‐nearest neighbours (n.n.n.) F − ions are determined. Using ENDOR‐induced ESR it could be shown that the cubic field splitting parameter has the same (positive) sign as the n.n. neighbour shf interaction. Weak satellites in the ESR and ENDOR‐induced ESR spectra are tentatively assigned to a hf interaction with the 2.2% abundant 57 Fe nucleus. The interpretation of the shf data in terms of a covalency and overlap model shows that the n.n.n. shf interaction can be explained as a transferred shf interaction via F − –F − ion core overlaps.