FERRIMAGNETISM IN FINE FEROXYHITE PARTICLES

Mossbauer spectra of feroxyhite (delta'-FeOOH) fine particles subjected to strong magnetic fields have been measured at 4.2 K. It is shown that the behaviour is consistent with ferrimagnetism; the assumption that the anisotropy and exchange fields are single-valued provides good agreement with the data. Consequently, the effects of any surface ions with different magnetic states appear to be absent. Differences between samples are ascribed to atomic disorder which depends on the conditions of sample preparation.