Detection of Magnetic Particles by Magnetoresistive Sensors

A. Weddemann[1], A. Auge[1], F. Wittbracht[1], C. Albon[1], and A. Hütten[1]
[1]Department of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, Bielefeld, Germany

In this work, we demonstrate the implementation of the micromagnetic equations for the description of ferromagnetic thin films in COMSOL Multiphysics®. We apply our model to magnetoresistive sensors consisting of several soft ferromagnetic layers and their response to magnetic particles. The magnetization dynamic of the particles needs to be described in a similar manner, though due to size effects it is possible to reduce the description to a set of ordinary differential equations. The signal will be discussed in respect to the particle position as well as the influence of antiferromagnetic ordering in particle clusters that are within detection range.

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