Further, the effect of the polymer coating on the magnetic properties was studied at 5 and 300 K, and the results are summarized in Table . It is evident that as the temperature raised, both the Hc and the MR decreased to near zero at room temperature, which indicated the maintenance of the SPM regime as in the initial MNPs. Overall, the increase in Mn 2+ content slightly raised Ms values at room temperature, except for the sample with the highest Mn 2+ content, confirming the tendency found for the initial MNPs. It is worth mentioning that Ms values were slightly higher (85.0 -89.0 Am 2 /kgferrite) than those of Fe3O4 MNPs (82 Am 2 /kg) obtained under the same synthetic procedure at 300 K (Figure ) and those of initial samples (Figure ), confirming that polymer coating influences the rearrangement of ions on the MNPs surface . Changes in the magnetic properties after surface modification have been previously reported when using different polymers such as triethyleneglycol (TEG) and polyethyleneglycol (PEG), probably due to the reduction of spin canting effect . This is not exactly our case, as PMAO polymer is not directly coordinated to the iron ions but intercalated in the OA chains; nonetheless, PMAO coating promoted ions leaching and thus, the rearrangement of cations on the MNPs surface . The enrichment Mn 2+ cations in the outer part of the MNPs is reinforced by the fact that, in such distribution, the spins close to the surface are canted and barely contribute to the Ms in the quasi-static regime, explaining the unalterable Ms values with increasing Mn 2+ content. The spin canting effect dictated by the heterogeneity of allocation of Mn 2+ cations could still play a major role in reducing the average HC and MR, which is important for applications dependent on surface properties such as AC hysteresis and relaxometry . a Determined as the field at which the magnetization of the magnetized and the demagnetized branches differs in 3% of Ms .