Abstract
The ferrimagnetic spinels , Ni, Co, Mn, and Mg have been prepared and studied with the Mössbauer-effect technique over a wide temperature range both with and without large applied magnetic fields. The cation distributions have been determined and compared with magnetization measurements. For Co and Mg, this distribution depends on the heat treatment; two extremes—quenched and slowly cooled samples—have been investigated. The hyperfine magnetic fields at nuclei in and sites have been obtained as a function of temperature. A number of hyperfine fields are identified with the sites of Co, Mn, and Mg and attributed to the kind and distributions of cations in the nearest-neighbor sites. From the data, the ratio of the and to the superexchange interactions is found to be 0.68 and 0.66, respectively. Since the Mössbauer spectra provides no evidence for ions in Mn, a canted spin arrangement for the Mn ions in and sites is proposed to account for the small observed magnetization.
- Received 26 May 1969
DOI:https://doi.org/10.1103/PhysRev.187.747
©1969 American Physical Society