Size-dependent transition from shape to exchange dominated magnetic nanostructure

In order to quantitatively investigate the interplay between shape anisotropy (magnetostatics) and exchange, patterned zigzag structures were prepared with sizes varying over two orders of magnitude. The magnetic state is a balance between shape anisotropy, which causes the magnetization to follow the serrated edge of the structure, and exchange, which prefers uniform magnetization. In intermediate-sized structures, we find that the magnetization along the center of the zigzag oscillates between approximately +/- 32 degrees and is relatively independent of the device size. As the dimensions are reduced to less than a critical length lambda(cr), the oscillation magnitude drops rapidly. On the other hand, the largest structures develop extended film properties such as multiple vortices and ripple. (C) 2006 American Institute of Physics.