A detailed understanding of magnetic noise behavior in magnetoelectric (ME) sensor structures is of fundamental interest for the realization of magnetic field sensors with ultra-low detection limits, as many promising sensor approaches of the CRC are presently limited in their performance due to magnetic noise. The aim of this project is to comprehend and quantify the influence of geometrical and physical imperfections as well as the connected magnetic microstructure on the magnetic noise of ME sensors. Defects of magnetic relevance include physical and geometrical deviations, which differentiate the real system from an idealized one. The nucleation and the behavior of magnetic domains and domain walls are highly related to the defect structure of the system. Examples of imperfections are local geometrical errors, non-uniform magnetic material properties, and local eigenstresses, all of which will influence the magnetic structure of the magnetic layers and its ME response characteristics.
To achieve the aforementioned goal, dedicated experimental methods, for example, time-resolved in-situ magneto-optical magnetic domain response analysis and local noise measurements, will be combined with high-resolved and adaptive micromagnetomechanical simulations including adaptive discretization approaches and scale transition methods. For the modelling, transfer functions will be derived, revealing the influence of geometrical and physical imperfections on the measured noise. The influence of material properties, sensor designs, and fabrication processes will be investigated numerically and experimentally. Different ME sensor concepts under consideration within the CRC (electrically modulated, surface acoustic wave, and soft composite-based sensors) will be covered in combination with magnetic domain, general magnetic, and noise investigations on well-defined model structures exhibiting artificial imperfections and tailored micromagnetic features. Our strategy will permit achieving accurate and direct insights into the exact influence of imperfections on the magnetic domain behavior and thus the magnetic noise. From comparing the results, a fundamental understanding of the role of different scales in time, depending on the operational frequency, and space will be developed. From the relevance to the magnetic noise behavior, we will derive targeted strategies for noise reduction as well as identify possible feasibility limits.