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Full-Text Articles in Nanoscience and Nanotechnology
Large Coercivity In Nanostructured Rare-Earth-Free Mnₓga Films, Don Heiman, Tom Nummy, Steve Bennett, Tom Cardinal
Large Coercivity In Nanostructured Rare-Earth-Free Mnₓga Films, Don Heiman, Tom Nummy, Steve Bennett, Tom Cardinal
Donald Heiman
The magnetic hysteresis of MnₓGa films exhibit remarkably large coercive fields as high as μₒHC=2.5 T when fabricated with nanoscale particles of a suitable size and orientation. This coercivity is an order of magnitude larger than in well-ordered epitaxial film counterparts and bulk materials. The enhanced coercivity is attributed to the combination of large magnetocrystalline anisotropy and ~50-100 nm size nanoparticles. The large coercivity is also replicated in the electrical properties through the anomalous Hall effect. The magnitude of the coercivity approaches that found in rare-earth magnets, making them attractive for rare-earth-free magnet applications.
Magnetic Properties Of Gamnas Nanodot Arrays Fabricated Using Porous Alumina Templates, S. Bennett, L. Menon, D. Heiman
Magnetic Properties Of Gamnas Nanodot Arrays Fabricated Using Porous Alumina Templates, S. Bennett, L. Menon, D. Heiman
Donald Heiman
Ordered arrays of GaMnAs magnetic semiconductor nanodots have been fabricated using anodic porous alumina templates as etch masks. The magnetic behavior is studied for prepared arrays with 40 nm dot diameter, 15 nm dot thickness, and 80 nm periodicity. The disklike nanodots exhibit an easy axis for fields applied in the radial direction and a hard axis in the smaller direction. In the radial direction superparamagnetism is observed with a blocking temperature of 30 K. The fabrication technique is convenient for preparing nanodot arrays of compound semiconductors that cannot be formed by self-assembly techniques.