Nanoscale Magnetic Imaging and Multilayer Engineering for High-Sensitivity Solid State Sensors
Abstract: The precise mapping of magnetic stray fields at the nanoscale is essential for understanding the local behavior of low-dimensional materials and for developing high-sensitivity spintronic devices. In the first part, I employ nitrogen-vacancy (NV) center diamond microscopy for non-invasive stray field imaging of spin-crossover (SCO) molecules and WS2 2D materials. By measuring the local magnetic environment with nanoscale resolution, I resolve magnetic signatures of molecular spin states and edge-localized stray fields in flakes with thicknesses ranging from 45 to 160 nm. This approach enables the detection of magnetic textures that are typically inaccessible via conventional bulk techniques.
In the second part, I focus on the microfabrication and optimization of Magnetic Tunnel Junction (MTJ) sensors for ultra-high sensitivity at room temperature. This is achieved by utilizing laminated magnetic films to reduce coercivity and saturation fields while slightly pinning the free layers perpendicular to the sensing axis to ensure superior room-temperature performance.
Together, these advancements illustrate how high-resolution stray field imaging and strategic multilayer design provide the necessary tools to characterize and optimize the next generation of solid-state magnetic systems.