Effects of covalency on magnetic properties of tetrahedral V4+ ion in garnets

The theory of covalency is applied to the discussion ofg-factors and hyperfine constantsA of a V⁴⁺ ion in tetrahedral sites in garnets Ca₃X₂Ge₃O₁₂ with X=Sc, Al, Lu, In, and NaCa₂. Mg₂V₃O₁₂, Ca₃Sc₂Si₃O₁₂, Sr₃Sc₂Ge₃O₁₂. The site symmetry is S₄. Coefficients in LCAO-MO wave function and the Fermi contact interaction constantx are determined by an iterative procedure from experimental data. The spin-orbit coupling coefficient _d and radial average r ^–3 are deduced from the condition of solvability of four equations: overlap and charge-transfer integrals are also determined.The author is grateful to Dr. P.Novák for many valuable discussions on the subject and Dr. J.Jokl from the Institute of Macromolecular Chemistry of Czechoslovak Academy of Sciences for optical measurements.