R. A. Lukaszew

University of Toledo

"Highly anisotropic nanomagnets"

Nanomagnetism is very active area of research because of fundamental interest as well as novel applications. One of the driving applications is the development of new perpendicular magnetic media that can satisfy the demands for ever increasing data storage density. This new media for perpendicular magneto-recording must satisfy three important requirements: (1) the material must have large magnetic anisotropy to withstand the superparamagnetic limit upon size reduction, (2) the magnetic anisotropy must be perpendicular to the surface and (3) these two conditions must subsist upon nano-patterning. Two main approaches are currently being investigated by several groups in order to achieve nano-patterning while preserving the two other conditions using these alloys. "Top-down" methods involve self assembly of alloy magnetic nano-particles and in "bottom-up" methods the material is deposited and nano-patterning is induced during growth. In my talk I will present two variations of the bottom-up approach. First I will show correlated structural and magnetic properties studies on epitaxial FePd films grown on (001) MgO. This particular system does exhibit perpendicular magnetic anisotropy and it is also nano-structured due to 3-dimensional growth mode on the chosen substrate. The highly-ordered nanostructures embedded in the chemically disordered alloy film are magnetically coupled. Capping the films with a thin MgO layer significantly lowers interparticle coupling. For the FePt system we have exploited ion-implantation of Fe ions on epitaxial Pt films followed by rapid thermal treatments. We have achieved controlled nano-patterning and large perpendicular magnetic anisotropy. I will present our correlated structural (XRD, AFM, TEM) and magnetic (MFM, Kerr magnetometry) characterizations on the two systems studied.

Thursday, March 30, 2006

4:10 p.m. -- Walter Lecture Hall 245