Magnetic Properties and Mössbauer Spectroscopy of FeO/CoFeO Nanorods.

FeO/CoFeO nanorods were obtained via a simple seed-mediated synthesis. Nanorods were used as seeds to grow CoFeO by thermal codecomposition of the cobalt(II) and iron(III) acetylacetonate precursors. The growth process was monitored by electron microscopy (SEM, TEM), and the resulting nanorods were characterized by powder X-ray diffraction analysis and IR and Raman spectroscopy. Magnetometry and AC susceptometry studies revealed a distribution of Néel relaxation times with an average blocking temperature of 140 K and a high-field magnetization of 42 Am/kg. Complementarily recorded Fe-Mössbauer spectra were consistent with the FeO/CoFeO spinel structure and exhibited considerable signs of spin frustration, which was correlated to the internal and surface structure of the nanorods.