Critical influence of different diamagnetic ions on electromagnetic properties of BaFe12O19

The correlation between the electromagnetic properties of BaFe12-xDxO19 (0.1⩽x⩽1.2) solid solutions (D = Al3+, In3+ and Ga3+) and the concentration of diamagnetic ions was investigated. The changes of electromagnetic properties of the investigated samples were explained using neutron powder diffraction and Mossbauer spectroscopy data. The diamagnetic ions with different ionic radii and electronic configurations were chosen. The transmission spectra of all the samples demonstrated a deep minimum in the frequency range 20-65 GHz which was associated with the natural ferromagnetic resonance. The resonance frequency fres and amplitude were changed by the substitution type and level. With increasing the substitution concentration, the resonance frequency increases from 51 GHz to 61 GHz and decreases from 50.5 GHz to 27 GHz for Al- and In-substituted samples, respectively. More complicated concentration dependences of resonance characteristics were obtained for Ga-substituted samples in a narrow range of 49-50.5 GHz. The value of fres had a minimum around x = 0.6 and further increased to 50.5 GHz for x = 1.2. It was concluded that the intrasublattice interactions were responsible for tailoring the magneto crystalline anisotropy and resonance parameters. More detailed investigations would require the development of phenomenological model on the basis of the electronic structure using Goodenough-Kanamori approaches.