Magnetization reversal study on patterned ferromagnetic and exchange-biased systems

Magnetic force microscopy (MFM) with in situ magnetic fields and magnetooptical Kerr microscopy (MOKE) combined with micromagnetic simulations and analytical calculations were used to study the magnetization reversal in three systems; ferromagnetic Ni nanopillars, permalloy elliptical particles, and exchange biased permalloy elliptical particles.;The data from patterned ferromagnetic Ni nanopillars were used to develop a method to quantify both the magnetostatic interactions and the disorder present in magnetic particle arrays; the model is based on numerical calculations of an Ising-like system.;In the investigation on nanometer sized permalloy elliptical particles, switching the particles' magnetizations with pulsed magnetic fields in the presence of a static applied field at room temperature a large pulse time and field magnitude variation between particles was found.;MOKE was used to investigate the magnetization reversal in individual elliptical permalloy particles with exchange bias as a function of the angle between the shape induced anisotropy and exchange bias anisotropy axes. Both the tilt and the contraction of the Stoner-Wohlfarth astroid observed could be well understood by a simple analytical energy density equation minimization. The asymmetric magnetization hysteresis loops were enhanced by increasing the angle between the shape anisotropy and the exchange bias anisotropy directions.