The magnetic behaviour of two ferromagnetic oxides and two ferrimagnetic oxides (ferrites) are compared to study the effect of magnetocrystalline anisotropy on thermal-history-dependence of magnetization of these ordered magnetic systems. All four compounds show thermomagnetic irreversibility (MFC >MZFC) below a certain temperature,Tirr. The highly anisotropic ferromagnetic oxide, SrRuO3 and the hard ferrite, SrFe12O19 show sharp peaks belowTc in theirMZFC(T) curves, whereas for the soft ferrite Ni0.8Zn0.2Fe2O4 and the low anisotropic ferromagnetic oxide La0.7Ca0.3MnO3 only a broad maximum is observed inMZFC, when measured in small magnetic fields. The shapes of theMZFC(T) curves are inversely-related to the magnitude of the coercivities (Hc) of the compounds in relation to the applied field, and the temperature dependence of Hc.MFC andMZFC are related through the coercivity for all four magnetic systems.
Volume 42 | Issue 5
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