Magnetic State in Nanostructured ZnFe$_2$O$_4$ at Low Temperature

Nanostructured ZnFe$_2$O$_4$ prepared by high-energy ball milling process for 4 h, showed spontaneous magnetization below 460K,while bulk ZnFe$_2$O$_4$ has antiferromagnetic state below 10K. Magnetic state in this ball-milled ZnFe$_2$O$_4$ at low temperature was investigated by observing the behavior of spectrum of zero-field nuclear magnetic resonance with applying external magnetic field and varying temperature. In addition to verifying ferrimagnetic state that is naturally expected, we found the co-existence of antiferromagnetic long range ordered state in octahedral site. Canted state appeared only in magnetization of octahedral site that consists of the ferrimagnetic state.