Title: Micromagnetic studies of vortices entering nanoscale structures

Abstract: The magnetization patterns of a symmetric object at high fields 
and the LLG equations both have inversion symmetry. At low fields the 
symmetry of the magnetization pattern is broken. The development of 
handedness and a polarization axis are prelude to the entry of a vortex 
through a surface.

The vortex is a relatively simple object with most of its degrees of 
freedom suppressed, yet complex enough to be interesting as a model 
system. The entering vortex illuminates the role of surface phenomena and 
thermal activation in providing and overcoming barriers. Among the objects 
studied are square cross section nanoboxes, parallelepipeds, and 
ellipsoids with three unequal axes.  The symmetry-breaking vortex 
configurations have a direct correspondence to the Landau configuration in 
a parallelepiped