Magnetic Micro- and Nanostructures for Sensor Applications

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The project aims at developing micro- and nano-scale tubular magnetic field sensors by rolling magnetic nano-membranes, which detects small magnetic fields in a medium flowing through the tube and can be integrated with other sensor elements on the same tube section. Fundamental theoretical and experimental studies are planned to elucidate the microscopic coupling phenomena in the geometrically induced giant magnetoresistance effect ( GMR), which is the basic measuring principle of the sensor. For further optimizing the sensor function, deviations from the domain structure and the resonant modes of the planar initial film caused by the rolling up will be determined. For that purpose the magnetization of the ferromagnetic layer will locally be modified by ion irradiation such that magnetic segments of different spatial arrangement are defined along the tube. A systematic variation of the dimensions of the tube will allow to analyzing the geometric effects of rolling on the GMR effect. The proposed development of the soft X-ray tomography technique offers a worldwide unique access to three-dimensional detection of complex vector fields as the ones encountered in magnetism and magnetic detection. Secondly, it is also an ideal starting point for a scale-adapted modeling, which embeds the magnetic functionality of complex-shaped detector geometries into classical device simulation. Finally, the joint expertise gained during the first phase of the research group within of the subprojects TP6 and TP8 will be exploited to prepare a multifunctional rolled-up element, which combines optical and magnetic detection capabilities and poses the very first attempt towards "lab-in-a-tube" concept.