Project Details
Projekt
Scanning Nitrogen-Vacancy Centre Magnetometer
Subject Area
Condensed Matter Physics
Term
Funded in 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 506455202
Quantum mechanical systems are inherently highly sensitive to external disturbances. This makes them ideal candidates for applications as sensors. Quantum sensors have gained significant interest in the development of novel technologies for measuring physical properties such as electromagnetic fields, thermodynamic properties such as temperature, and mechanical properties such as rotation. Compared to conventional sensing techniques based on classical physics, the key benefit of quantum sensors is their high precision. Here, we propose using a scanning nitrogen-vacancy (NV) centre microscope for sensing magnetic fields with ultra-high spatial and temporal resolution. A scanning NV magnetometer combines an optical confocal microscope with an atomic force microscope. A single negatively charged NV defect at the apex of a diamond atomic force microscopy tip is used as an atomic-sized sensor for measuring magnetic fields. For this, the quantum spin state of the NV centre is initialised optically and interacts with the magnetic field in a well-characterised manner. The resulting spin state is read out using optically detected magnetic resonance spectroscopy. This allows for precise and quantitative determination of the magnetic fields under ambient conditions with an easily detectable field of 5-10 µT. By scanning the sharp tip across the sample surface, the scanning NV magnetometer simultaneously records a map of the sample topography and the magnetic field present at the surface with a spatial resolution of down to ~10 nm. In addition to continuous optical and microwave pumping for measuring DC magnetic fields, pulsed measurement using established sequences of optical and microwave pulses allow for higher magnetic field sensitivity down to 0.5-1 µT as well as temporal resolution up to the GHz regime. NV centres' long and environment-dependent coherence times enable noise spectroscopy via spin relaxometry. Conventionally used techniques to image magnetization on the nanoscale such as spin-polarised scanning tunnelling microscopy and X-ray spectroscopy require dedicated sample preparation and complex experimental setups. Alternative techniques such as magnetic force microscopy are based on sensing stray fields. However, most of these techniques are perturbative and are not easily quantifiable. The key benefits of scanning NV microscopes are their wide compatibility with different samples and environments, and the non-perturbative nature of the measurement. Our proposal team has a diverse background with expertise in molecular spintronics, novel magnetic materials and NV magnetometry. We propose to make use of the unique features of the highly versatile scanning NV magnetometer setup for a wide spectrum of research projects ranging from imaging spin textures in magnetic materials in combination with magneto-transport measurements to detecting nuclear magnetic resonance in molecules.
DFG Programme
Major Research Instrumentation
Major Instrumentation
Stickstoff-Fehlstellen-Zentrum Rastersonden-Magnetometer
Instrumentation Group
0150 Geräte zur Messung der magnetischen Materialeigenschaften
Applicant Institution
Johannes Gutenberg-Universität Mainz
