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Magnetic properties of nanowires obtained by electrodeposition AC

Grant number: 05/00931-8
Support type:Regular Research Grants
Duration: September 01, 2005 - August 31, 2007
Field of knowledge:Physical Sciences and Mathematics - Physics
Principal Investigator:Daniel Reinaldo Cornejo
Grantee:Daniel Reinaldo Cornejo
Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil


In the last years there has been great interest in the synthesis and characterization of one-dimensional (1D) structures. Particularly, nanowires of magnetic materials constitute an important class of 1D nanostructures being very interesting as possible patterned perpendicular media of data storage. Nanowires of elements, oxides, nitrides, carbides and other composts can be generated by employing various chemical or physical techniques. Masuda and Fukuda (Science 268, 1995) were pioneers in the fabrication process of highly ordered arrays of nanoholes in membranes of alumina by the so-called two-steps anodization method. These arrays of self-ordered holes show a well defined hexagonal structure, with diameters of pore and interpore distances in the nanometric scale. Using an electrodeposition ac process it is possible to fill such holes with metals such as Fe, Co and Ni. In this manner, arrays of magnetic nanowires with high anisotropy of shape can be obtained. As it was mentioned, these materials are promissory for perpendicular magnetic media, because the density of nanowires in the array can, in principle, be so high as 10E11-10E12 pore/in2. This means that these arrays of nanowires possess a potential density of 100-500 Gbits/in2. On the other hand, these self-assembled ferromagnetic nanowire arrays are ideal systems to study mesoscopic magnetism, because their radii and separation between wires, being of a few nanometers, are comparable to the magnetically interesting length scales in the system. Then, many phenomena and properties can be explored and explained in these new materials, since some basic aspects of the thermodynamic governing the formation of the nanoholes in membranes, until relations involving the magnetic interactions between nanowires and its fundamental magnetic characteristics. The aim of this project is the preparation of nanowires of Fe, Co and Ni, and the study of its static and dynamic magnetic properties. The nanowires will be obtained by electrodeposition ac in ordered porous alumina arrays previously anodizated by the two-step anodization approach... (AU)