Magnetic relaxation in spinel Mo-ferrite and Ti substituted Mo-ferrite

Abstract:

A compensation temperature of 138 K was observed in the temperature-dependent magnetization curves of MoFe₂O₄. Relatively slow magnetization relaxation characterized the transitions between different spin states (compensated and uncompensated). Large magnetic after effect was found in time-dependent magnetization curves after heating or cooling from different characteristic temperatures for different spin states. The magnetic relaxation was nearly independent on magnetic field, supporting the presence of spin states and no involvement of domain structure. For the Ti substituted Mo_0.6Ti_0.4Fe₂O₄ sample, there were a compensation at ∼ 100 K and a maximum of magnetization at ∼ 175 K. Similar results of anomalous magnetic relaxation was observed in Ti substituted Mo-ferrite (Mo_0.6Ti_0.4Fe₂O₄). If the Mo_0.6Ti_0.4Fe₂O₄ sample was heated from 100 K to 235 K, the time-dependent magnetization curve could be considered as a combination of two magnetic relaxation processes. However, if the sample was heated from 100 K to 295 K, the time- dependent magnetization curve became complex.