Magnetic properties of Zn-ferrites obtained from multilayer film deposited by sputtering.

K. L. SALCEDO RODRÍGUEZ; C. E. RODRÍGUEZ TORRES

Buenos Aires

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

Nowadays, transition metal oxides films generate great interest because they may behave as insulators, semiconductors, superconductors and metallic conductors, depending on several factors including the synthesis process in which variables as the pressure and temperature of the substrate play a great role. Another relevant factor is the change in the properties of different complex oxides in contact with each other, because of phenomena that occur at the interface – as for example: broken symmetry (electronic and structural properties), potential difference (charge transfer) - and in the case of multilayers, in the regions remote from the interface where unshielded interactions can influence the properties of the samples and in which the relative thicknesses of the layers can be comparable to the length scale of phenomena located in the interface region. This has led to studies focused on the physical processes which occur in this kind of materials. Many recent studies focus on zinc ferrite due to the change of their properties and cation distribution at bulk or nano regimes, allowing different applications [2-4] In this work we present the study of the magnetic properties of thin films of zinc ferrites deposited by magnetron sputtering. Ferrites were fabricated from multilayer Zn-O and Fe-O, starting from Zn and Fe metal targets in oxygen atmosphere. We varied the number and the thickness of layers maintaining constant a total thickness of 200 nm and the sample stoichiometry. We found that samples where layers have thicknesses of the order of the nanometer (1nm Zn-O/ 2nm Fe-O; 40 layers) present magnetic properties similar to bulk ferrite: mainly paramagnetic at room temperature and antiferromagnetic below 10 K. Samples with thicker individual layers present superparamagnetism at room temperature. Blocking and irreversibility temperatures increase as layer thickness increases; this effect can be assigned to inhomogeneities in the iron distribution.