Magnetic properties of Ru-Ti doped Strontium hexaferrite nanocrystalline particles

We carried out a systematic study on the effect of the substitution of Ti$^{\mathrm{2+}}$ and Ru$^{\mathrm{4+}}$ ions for Fe$^{\mathrm{3+}}$ ions on the magnetic properties of the strontium ferrite SrFe$_{\mathrm{12-2x}}$Ru$_{\mathrm{x}}$Ti$_{\mathrm{x}}$O$_{\mathrm{19}}$ nanoparticles with ($0\le x\le 1)$, using vibrating sample magnetometry, electrical resistivity, and M\"{o}ssbauer spectroscopy. A clear irreversibility between the zero-field-cooled and field-cooled curves was observed below room temperature and the zero-field-cooled magnetization curves displayed a broad peak at a temperature T$_{\mathrm{M}}$. These results were discussed within the framework of random particle assembly model and associated with the magnetic domain wall motion. The resistivity data show some kind of a transition from insulator to perfect insulator around $T_{M} $. With Ru-Ti substitution at 5 K, the saturation magnetization showed small variations were it slightly increased up to x $=$ 0.2 and then starts to decrease for x between 0.2 and 0.5, while the coercivity decreased monotonically, recording a reduction of about 93{\%} at x $=$ 0.4. These results were discussed in light of the single ion anisotropy model and the cationic distributions based on the results of the M\"{o}ssbauer spectroscopy data.