Lorentz microscopic investigations of micromagnetic structures

Magnetic materials are characterized mainly by their response to external magnetic fields, i.e. by hysteresis loops. These hysteresis loops are an averaged signal for the specimen, and the specimen is in most cases macroscopic. For new applications in microsystem components, the lateral dimensions of magnetic functional units will soon reach 0.1 μm and less, thus being in the dimension of micromagnetic structures such as local induction fluctuations. Therefore, severe influence of the lateral dimensions on the physical (magnetic) behaviour can be expected. Lorentz microscopy is a technique which can give the necessary information on micromagnetic properties at high spatial resolution. Some experimental results will be presented, which show both the capability of Lorentz microscopy to resolve the micromagnetic structure of modern multilayered thin films and also the necessity to look at the micromagnetic structure at a microscopic scale.