High-field Mössbauer study of manganese-zinc ferrites

The disordered ferrite system, ${\mathrm{Mn}}_{1-x}{\mathrm{Zn}}_x{\mathrm{Fe}}_2{\mathrm{O}}_4$ for $0\le x\le 0.95$ has been studied by the Mössbauer-effect technique at 4.2 K in applied magnetic fields of 50 and 90 kOe. In these fields a ferrimagnetic structure is implied for the entire family of compounds. For $x=0\mathrm{}$ the cation distribution is (${\mathrm{Mn}}_{0.82}$ ${\mathrm{Fe}}_{0.18}$)[${\mathrm{Mn}}_{0.18}$ ${\mathrm{Fe}}_{1.82}$]${\mathrm{O}}_4$; for larger $x$ the iron concentration on $A$ (tetrahedral) sites decreases, and becomes less than 2 at.% by $x=0.6\mathrm{}$. For $x\ge 0.6$, some of the Fe ions on $B$ (octahedral) sites have their spin moments reversed. Within the experimental error, the magnetic moments of the iron ions are collinear for $x<\mathrm{}0.5\mathrm{}$ and noncollinear for $x>\mathrm{}0.5\mathrm{}$. The canting angles for normal $B$-site cations are found to increase with increasing zinc content, and to depend on the applied field. The sample with $x=0.80\mathrm{}$ has the most stable structure. The hyperfine fields and isomer shifts show only a small variation with sample composition.