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Mer. 29/10/2025 14:00 Amphi Physique, Bâtiment 20, RdC (à confirmer) SFEIR Elias (L2C) Towards multimodal sensing with a scanning NV center microscope Measuring physical quantities at the nanometer scale is essential for investigating the properties of materials, which requires a versatile microscopy technique. In this context, scanning NV center microscopy emerges as an ideal candidate, as it exploits the unique spin and optical properties of the nitrogen-vacancy center in diamond to achieve quantum sensing with high spatial resolution and sensitivity. Importantly, the NV center is sensitive to multiple physical quantities, including magnetic and electric fields, temperature, and pressure. This approach has already proven to be efficient for magnetometry, capable of imaging static magnetic field with a sensitivity of about 5 μT/√Hz and a spatial resolution of 50 nm. In this thesis, the technique was first applied to the investigation of the effect of confinement in the van der Waals ferromagnet Fe5GeTe2 by performing quantitative maps of the stray field generated by patterned microstructures. This study revealed that geometrical confinement does not affect the Curie temperature, but favors the stabilization of magnetic vortices in microstructures. The second part of this thesis focuses on extending scanning NV center microscopy to nanoscale thermometry, specifically for microelectronic characterization, with the objective of determining its ultimate performance in terms of sensitivity and spatial resolution. This work shows that the thermal sensitivity of the technique can reach a few hundred mK/√Hz. Nevertheless, the measurements also revealed several limitations. These include perturbations from parasitic magnetic fields generated by current-carrying structures, imperfect thermal contact with the sample leading to non-local temperature measurements under ambient conditions, and thermal dissipation associated with the large diamond volume of the probes. Finally, COMSOL simulations show that the most effective configuration remains a nanodiamond in direct contact with the heat source. This explains why, to date, scanning NV thermometry using nanodiamonds attached to the probe remains the most efficient approach. Pour plus d'informations, merci de contacter Finco A. |
