Magnetostrictive multilayers for magneto-electric sensors - layer structure and magnetic domains

• Applicants: Professor Dr.-Ing. Jeffrey McCord; Dr. Dirk Meyners
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2015 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269913640

The focus of the project is research on novel magnetostrictive components for magneto-electric 2-2 structures with a strong emphasis on the relevant magnetic domain processes for highly sensitive magnetic field sensors in different application scenarios. Within the project, the conditions for the use of known and also new magnetic materials, material combinations, and alternative approaches for the preparation of optimized magneto-electric composites are to be evaluated. For this purpose sputtered magnetic multilayer film systems with high piezomagnetic coefficients will be investigated. In addition to the influence of the effective magnetic material parameters on the magneto-electric response, the influences of the microstructure and the associated magnetic domain structure will be central to our studies in order to achieve a low limit of detection for the sensors. Interfacial and magnetostatic coupling phenomena are used to control the behavior of the magnetostrictive phase of the sensors.Through modeling and spatially resolved magnetic characterization methods, an understanding of the functional relevant magnetic processes of structured magneto-electric multilayers will be achieved. Known limitations in the detection of low frequency signals through exhibited Barkhausen noise will be eliminated. Therefore, e.g. in combination with exchange biased layers, novel layer systems will be systematically investigated. A special emphasis of the research lies in the analysis of the influences of different processing parameters on magnetic domain structure and the corresponding sensor noise exhibited by the devices. Fundamental knowledge obtained from simple model structures will be transferred to technical sensor structures. Moreover, innovative material combinations that can withstand higher processing temperatures will be investigated. In order to achieve high thermal stability together with high piezomagnetic coefficients FeCo/TiN multilayer structures will be explored. Moreover, alternative approaches for sensor structures with highest sensitivity will be investigated. The material and physical foundations for highly sensitive magneto-electric sensors will be developed. The results of the research are expected to lead to 2-2 magneto-electric composites with greatly improved magnetic properties.

• DFG Programme: Research Grants