Issues in Nano-Magnetism
R. Ale Lukaszew
University of Toledo, Physics & Astronomy Department
The correlation of structure and magnetism in magnetic materials continues to offer exciting opportunities for the formation of new magnetic nano-structures with unusual magnetic properties. For example the fabrication of novel magnetic materials in thin film form has led to enhancement of magnetic anisotropy, giving rise in some cases to perpendicular magnetic anisotropy or enhanced magneto-optical behavior. Thus, research on nano-magnetism is driven by its fundamental scientific importance as well as the requirements of the magneto-recording industry. The latter has projected stored areal-data-densities in the tera-bit/inch-square range for the next few years. As areal density grows at unprecedented rates, information is stored in smaller and smaller magnetized regions on the hard-drive disc. It is increasingly difficult to obtain stable smaller nano-magnets, because of the superparamagnetic limit, where thermal fluctuations can produce a ‘flip’ in the magnetization state ‘stored’. Other challenges involve the development of sensors that can detect the magnetization state in nano-bits. I will present some of our studies in the area of nano-magnetism including the development of novel magneto-resistive sensors which has led to a patent.
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