Stray field of a Landau magnetization pattern

We present experiments and micromagnetic simulations on Hall micromagnetometry of magnetic vortices. The magnetization reversal in a 2 x 2 mu m(2) Permalloy square of 20 nm thickness is investigated at liquid helium temperatures. Nucleation, displacement, and annihilation of the vortex state in an external magnetic field are observed by detecting its stray field. The findings are corroborated by images taken with a magnetic-force microscope at room temperature. The experimental data are compared to micromagnetic simulations. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3000479]