(Autumn 2007, Associate Professor and VMEC Endowed Chair, College of William and Mary)
The correlation between structure and magnetism in magnetic materials continues to offer exciting opportunities at the nano-scale. For example the fabrication of novel magnetic materials in ultra-thin film form has led to perpendicular magnetic anisotropy and in some cases also enhanced magneto-optical behavior. In addition, understanding magnetic anisotropy is important to tailor desired properties for a given function. Thus, research on nano-magnetism is driven by its fundamental scientific importance as well as possible applications. For example, the magneto recording industry 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. There are natural limitations to this trend because it is increasingly difficult to obtain stable nano-magnets at ambient temperature, due to the super-paramagnetic limit, where thermal fluctuations can 'flip' the magnetic state 'stored'. New materials and schemes are currently being investigated to further push the present limit. Additional challenges involve fabrication of sensors that can detect the magnetization state in these nano-bits.
I will present some of our studies in the area of nano-magnetism including the development of novel magneto-resistive sensors and our recent structure-property correlations in highly anisotropic ferromagnetic nano-magnets.