TDPAC of γ-Rays Emitted from111Cd(←111In) in Fe3O4

The supertransferred hyperfine magnetic field, H STHF , at 111 Cd(← 111 In) on the tetrahedral site of Fe 3 O 4 was measured by means of the time differential perturbed angular correlation (TDPAC) between 85 and 300 K. Each TDPAC spectrum has a well-defined hyperfine frequency component above the Verwey temperature, T V (=120 K), whereas remarkably distributed one below this temperature. The value of H STHF at low temperatures is +121 kOe in average, which shows the covalence in Cd 2+ O 2- bonds is considerably smaller than that in In 3+ –O 2- bonds in spinel type oxides. The apparent distribution of the hyperfine frequencies below T V is qualitatively explained by a distribution of H STHF at 111 Cd due to fluctuation of the relative populations of Fe 3+ and Fe 2+ ions in the neighboring octahedral sites, or a small amount of electric field gradient acting on 111 Cd in addition to H STHF .