Ionic Distribution and Ferrimagnetic Resonance in Magnesium Ferrite

Three different ionic distributions have been achieved in the same magnesium ferrite single crystal sphere by appropriate heat treatment. The magnetic moment, anisotropy constants, $g$ value, and magnetic resonance half‐width have been measured as a function of temperature from −200°C to +250°C for the different ionic distributions. The treatments resulted in saturation magnetizations of 1.28, 2.23, and 1.41 Bohr magnetons, respectively. At nitrogen temperature ${\mathrm{|K}}_1|$ was observed to be higher for higher values of the magnetization in agreement with Folen and Rado. We find for the ferric ion cubic field splitting parameter $a$ , the values −0.0104 cm⁻¹ for the $A$ site and +0.0174 cm⁻¹ for the $B$ site. The resonance half‐width depends on the crystalline direction and was narrower in the hard [100] direction for the original ionic distribution. Successive treatments broadened the half‐width in the hard direction while the easy direction [111] remained relatively unchanged. After the treatments the narrower half‐width was observed in the easy direction. The room temperature $g$ value of about 2.01 was relatively independent of the ionic distribution. A slight dependence of $g$ value on temperature was observed.