Synthesis and magnetic characterization of ZnFe₂O₄ nanostructure in AAO template

One-dimensional-magnetic nanostructures have recently attracted much attention because of their intriguing properties that are not displayed by their bulk or particle counterparts. One of the commonly used methods for generating ID-nanostructures is based on the electrodeposition of various materials in porous membranes. This technique has been applied to fabricate metallic nanowires as arrays of wires perpendicular to the substrate. They display unique magnetic properties (e.g., anisotropic magnetization). Electrodeposition is, however, of limited use for oxide-based magnetic materials, due to the difficulty involved in the formation of oxides through electrochemical deposition. We obtained zinc ferrite nanowires inside an anodic aluminum oxide (AAO) template using a novel technology fundamentally different from electrodeposition. First, fabricated zinc ferrite nanoparticles were injected in the AAO template and then annealed in air. The process of embedding particles into the pores was assisted by the magnetic field of a permanent magnet placed under the substrate. The physical and chemical properties of these zinc ferrite nanowires have been investigated by thermogravimetric analysis, infrared, X-ray diffraction, scanning electron microscope, and superconducting quantum interference device. The nanoparticles embedded into the pores exhibited superparamagnetic behavior with the blocking temperature of 15 K. After annealing, the particles formed nanowires and the hysteresis of the annealed samples increased significantly.