Magnetic properties of ZnO-core/CoFe2O4-shell nanoparticles

D. TOBIA; G. C. LAVORATO; E. LIMA JR.; E. WINKLER; R. D. ZYSLER

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

Novel magnetic materials for specic 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 eects [1]. 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 eld-cooling and eld-cooling procedures were performed for dierent applied elds. At room temperature the particles show a superparamagnetic response while exhibiting a blocking temperature at 100 K. At 5 K, the coercive eld (HC) was found to be 8 kOe. The behavior of the blocking temperature and the coercive force as a function of the applied eld 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 [2]. [1] G. Schmid, Nanoparticles: From Theory to Applications, Wiley-VCH (2004). [2] E. Lima Jr., E.L. Winkler, D. Tobia, H.E. Troiani, R.D. Zysler, E. Agostinelli, and D. Fiorani, Chem. Mater. 24, 512 (2012).