The magnetic domain effect in the local canted spin ferrite Zn_0.5Co_0.5Fe_2-xCr_xO₄: A macroscopic and mesoscopic study

Abstract

AC susceptibility, zero-field-cooled (ZFC) magnetization and field-cooled (FC) magnetization have been reported for the Zn0.5Co0.5Fe1.1Cr0.9O4 disordered ferrite system. A polarization analysis of the transmitted neutron beam in both ZFC and FC conditions has also been reported for Zn0.5Co0.5Fe2-xCrxO4(x=0.9 and 1.0) systems. The low-field AC susceptibility shows a broad peak at a temperature (well below the Neel temperature) where a strong irreversibility between the ZFC and FC curves starts. The presence of a ferrimagnetic-like domain structure over the entire temperature range (below the Neel temperature) is confirmed from the presence of significant depolarization up to 12 K, the lowest measured temperature. The observed features of chi AC, magnetization and neutron depolarization measurements have been analysed using a model of thermally activated domain wall movement of ferrimagnetic arrangement of local canted spins.

Local canted spin behaviour in Co1.4−x Zn x Ge0.4Fe1.2O4 spinels: A macroscopic, mesoscopic and microscopic study

“…The above discussion shows that the characteristic behaviours observed in low field magnetization (figures 1 and 2) do not result from a breakdown of ferrimagnetic correlation or a transition to any spin glass-like phase but can be related to magnetic domain effects [9]. From our ZFC-FC magnetization and depolarization studies it is apparent that the growth and/or kinetic freezing mechanisms of magnetic domains depend on the exact cooling conditions (i.e.…”

“…The detailed description of the spectrometer has been given in earlier papers [7,8]. The temperature of sample was varied between 11 and 300 K in a closedcycle helium refrigerator and controlled to better than 0.1 K. The ZFC and FC neutrondepolarization measurements (with the same field values as applied for the ZFC and FC magnetization measurements) were carried out using the same procedure [9] as used for the present ZFC and FC magnetization measurements. In neutron depolarization experiments the amount of depolarization depends on the mean domain size AE, domain magnetic induction , neutron wavelength and the average number of domains AE along the path of neutrons (AE AE, where is the effective sample thickness) [8].…”

“…The procedure of obtaining È values from the measured flipping ratios for the transmitted polarized beam is described elsewhere [9]. For the Ü = 0.6 sample, both ZFC transmitted polarization and FC transmitted polarization show a continuous decrease right from 300 K and attain a constant value below about 100 K. The deviation between the ZFC and FC depolarization starts below about 260 K and the deviation increases with decreasing temperature.…”

“…However, for systems where long-range order is involved, such features can arise from domains, domain walls and also from disorder. In LCS systems such characteristic behaviors have been interpreted in terms of kinetic freezing of magnetic domains [1,4,9]. In order to identify the nature which the present materials possess some further clues are needed.…”

High-pressure growth and characterization of bulk MnAs single crystals

“…A full X-ray refinement was performed at room temperature on a crystal with dimensions system where long-range magnetic ordering is involved, the upturn in the FC curve can arise from domain-wall motions and/or disorder [38,39]. Cooling under the applied magnetic field favors domain growth in the direction of applied field, thus giving higher value of magnetization.…”