Observation of magnetization reversal of thin-film permalloy nanostructures using ballistic electron magnetic microscopy

We have imaged the magnetization reversal process of thin-film permalloy (Ni80Fe20) nanostructures using ballistic electron magnetic microscopy. Their switching behavior is often influenced by the formation of end domains and the subsequent domain-wall propagation under application of a magnetic field. Occasionally, this process leads to the formation of a 360° domain wall that is stable in fields which would otherwise switch the structure. The resulting state of the nanostructure in zero-applied field is very different from the near-single-domain state typically observed. The magnetization of the structure can show abrupt changes in a fixed magnetic field. © 2000 American Institute of Physics. @S0003-6951~00!02135-5#