Mechanism for nonuniform broadening of the NMR spectrum of orbitally degenerate centers in crystals with mixed-valence ions
Mitrofanov V. Ya. , Fishman A. Ya., Tsukerblat B. S.
A mechanism is proposed for the nonuniform broadening of the NMR spectrum of Jahn-Teller centers formed by mixed-valence ions. The effect stems from a nonuniform distribution of the net charge and of the spin density among the various nuclei of the impurity center upon the splitting of a degenerate term in the random crystal fields. This broadening is governed by isotropic hyperfine interactions and is distinct from the conventional mechanisms, which stem from anisotropic hyperfine interactions at Jahn-Teller ions.