Study of the Sublattices Magnetisations in Mn_0.6Zn_0.4Fe₂O₄ by Neutron Diffractometry and Mössbauer Spectrometry

Abstract

The temperature dependence of the two sublattices magnetisations of Mn,,,Zn,,,Fe,O, was determined in order to study the superexchange interactions in Mn2+-02+-Fe3+ linkages. The tetrahedral and octahedradl sublattices magnetisations were obtained in absolute scale by neutron diffractometry. Moreover by Mossbauer spectrometry the octahedral sublattice magnetisation was determined in a relative scale as il function of temperature. The results obtained by both methods show the same temperature dependences within the experimental accuracy. The Mossbauer spectra recorded a t temperatures higher than 100 O K show line broadening and overlapping indicating relaxation effects. The molecular field parameters were deduced from the experimental results on the basis of the N6el model. The best agreement is found for JAA = 0, JAB = (-19 f 1) OK, and JBB = (4.7 2) "K. The failing B moment and the evidence for a positive B-B interaction are discussed. Zum Studium des Superaustausches in Mn2+-02+-Fe3+-Zweigen haben wir die Temperaturabhangigkeiten der spontanenMagnetisierungen der beiden Untergitter des kubischen Ferrites Mn,,,Zn,,,Fe,O, bestimmt. Durch Neutronenbeugungsmessungen erhielten wir die Magnetisierungen der Tetraeder-und Oktaederuntergitter in absoluter Skalierung. Mit Hilfe des Mossbauereffektes haben wir die Magnetisierung des Oktaederuntergitters gemessen. Beide Methoden liefern iibereinstimmende Ergebnisse. Die Mossbauerspektren zeigen bei hoheren Temperaturen Linienverbreiterungen, die durch Spinflip-Prozesse gedeutet werden. Die Temperaturverlaufe der Untergittermagnetisierungen lassen sich durch eine Molekularfeldberechnung (NBelsches Modell) mit den Austauschparametern J A A = 0, JAB = (-19 5 1) O K und JBB = (4,7 & 2) "K beschreiben.

Neutron imaging for magnetization inside an operating inductor

“…The total magnetic moment for a unit chemical formula is roughly 2 μ B , which is almost the same as the value estimated from the bulk magnetization at room temperature (see details in the supplementary section). We can confirm that the microscopic magnetic states in the standby state agree with the previously reported results for bare Mn–Zn ferrites that have not yet been assembled in an inductor device 20 – 23 . In the subsequent section, we will consider how the ferrite core becomes microscopically magnetized when an exciting current is supplied to the copper wires.…”

Hyperfine Fields and Particle Size Distribution in Small Particle MnZn Ferrites

“…It is also known that MnZ+ ions show a strong preference for the A-sites. Mossbauer spectroscopic and neutron diffraction studies [20,21] have shown that Mn ions do not occupy the B-sites in the mixed ferrites MnxZn,-xFe,O,, for X 2 0.4. The ferrite sample Mn,.,Zn,,,Fe,O, used in this study has therefore the normal spinel structure: A-sites are occupied by Mn2+ and Znzt, whereas Fe3+ ions fill the B-sites only.…”

Mössbauer Spectroscopy Applied to Inorganic Chemistry

“…Konig et al 266 reported Mossbauer spectra on Zno.4Mno.6Fe204 at a number of different temperatures and suggested that the lineshape at, e.g., 300 K indicates a relaxational behavior. They ascribe this feature to the presence of Zn species which weaken the magnetic exchange interactions to such an extent that the frequency of the spin fluctuations becomes of the same order of magnitude as the rate of the nuclear Larmor precession.…”