Coexistence of ferrimagnetic and antiferromagnetic ordering in Fe-inverted zinc ferrite investigated by NMR

Abstract

The spin structure of nanocrystalline zinc ferrite synthesized via a high-energy ball milling process was investigated by nuclear magnetic resonance obtained at various external magnetic fields and temperatures. Iron inversion induced in nanosized zinc ferrite drastically changes its magnetic property. Nanocrystalline zinc ferrite shows ferrimagnetism below $460\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, while bulk zinc ferrite shows antiferromagnetism below $10\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We found that this antiferromagnetic order coexists with the ferrimagnetic order below $10\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ in nanocrystalline samples as well. A spin of Fe ion at the tetrahedral site is ferrimagnetically coupled with that at the octahedral site and the antiferromagnetism is found among the spins at the octahedral sites. The spins that participate in both of the ferrimagnetic and antiferromagnetic orderings at the octahedral site are canted.