Supertransferred hyperfine interaction: Perturbed angular correlation ofCdm111in antiferromagnetic NiO, CoO, and MnO

The time-differential perturbed angular correlation of ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}_{}^m{}_{}{}^{}$ substituted as a dilute impurity into antiferromagnetic NiO, CoO, and MnO has been observed. The following magnetic fields are found at the Cd nucleus (4°K): NiO (191.1 ± 2.5 kOe), CoO (170.8 ± 3.0 kOe), MnO (194.7 ± 2.5 kOe). They are compared with the Cd hyperfine fields in the antiferromagnetic perovskites KNi${\mathrm{F}}_3$:Cd, KCo${\mathrm{F}}_3$:Cd, and RbMn${\mathrm{F}}_3$:Cd reported earlier. The oxides are found to be more covalent than the fluorides. From the ratio of the hyperfine fields in MnO:Cd and NiO:Cd a new value of the spin density parameter $f_{\sigma }(\mathrm{Mn}-\mathrm{O})=8.1\%$ has been estimated.