Magnetic properties of ZnO-core/CoFe2O4-shell nanoparticles

DINA TOBIA; GABRIEL LAVORATO; ENIO LIMA JR.; ELIN WINKLER; ROBERTO ZYSLER

Buenos Aires

Workshop; X Latin American Workshop on Magnetism, Magnetic Materials and their Applications; 2013

Novel magnetic materials for specific applications require an accurate control and comprehension of their magnetic properties. Core-shell nanoparticles emerge as good candidates to future applications due to the possibility of tuning the magnetic properties through the interface interactions effects. In the present work, we present the synthesis and the magnetic properties study of ZnO-core/CoFe2O4-shell nanoparticles that consist of a non-magnetic core surrounded by a hard ferrimagnetic shell. The samples were obtained by high temperature decomposition of organometallic precursors followed by a seed-mediated growth method which led to nanoparticles of ~ 7.4 nm average diameter. Magnetization versus temperature measurements under zero field-cooling and field-cooling procedures were performed for different applied fields. At room temperature the particles show a superparamagnetic response while exhibiting a blocking temperature at 100 K. At 5 K, the coercive field (HC) was found to be 8 kOe. The behavior of the blocking temperature and the coercive force as a function of the applied field and temperature, respectively, were analyzed. Furthermore, the results are compared with previous studies of a CoO-core/CoFe2O4-shell hard magnetic system with similar morphology.