Program Highlights

Magnetization Reversal of Patterned Submicron-Sized Dot Arrays

L. Yuan, S.H. Liou
Nebraska MRSEC and
J. Moreland
NIST-Boulder

Ferromagnetic dots can have different reversal modes depending on their size. To gain a better understanding of this phenomenon, we have characterized the reversal process of an array of submicron-sized dots using magnetic force microscopy and microcantilever torque magnetometry - an ultrasensitive characterization device. Ni₈₀Fe₂₀ dots were patterned onto a silicon substrate and onto a magnetometry cantilever using e-beam or focused ion beam milling and lift-off process. The diameter of the dots is around 650 nm. The image below is an MFM image showing the domain structure of four of the dots. The magnetic moments in each dot are in a counterclockwise (white center) or clockwise (black center) state. The magnetic moments in the center of each dot are perpendicular to the plane of the dot-pointing into the page for the black centers, while the white centers point out of the page. The magnetometry results show how the magnetic moments change direction, which is important for the application of patterned arrays in nanoscale memory devices.
This research is supported by the National Science Foundation, Division of Materials Research, Materials Research Science and Engineering Program, Grant 0213808.