Nuclear Magnetic Resonance of Fe⁵⁷ in α-Fe₂O₃

Abstract

Nuclear magnetic resonance (NMR) of Fe⁵⁷ in α-Fe₂O₃ was studied by using both the steady-state method and the pulsed NMR method. The signal could be observed in the temperature range, where the sample shows the parasitic ferromagnetism. From the experimental results it was concluded that the NMR signal of this sample is due to the nuclei within the domain wall. The average enhancement factor of the applied rf magnetic field was measured to be about 25,000. The spin lattice relaxation time (T₁) of Fe⁵⁷ was distributed between 3 m sec and 100 msec at room temperature, depending upon the intensity of the exciting rf pulse. The values of T₁ could be qualitatively explained by the relaxation mechanism due to the thermal domain wall fluctuation.