  Dimensionality cross-over is a classical topic in physics. Surprisingly it
has not been searched in micromagnetism, which deals with objects such as
domain walls (2D) and vortices (1D). We predict by simulation a second-order
transition between these two objects, with the wall length as the Landau
parameter. This was conrmed experimentally based on micron-sized ux-closure
dots.

Materials Science