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- ItemVectorial calibration of superconducting magnets with a quantum magnetic sensor(Melville, NY : American Inst. of Physics, 2020) Botsch, L.; Raatz, N.; Pezzagna, S.; Staacke, R.; John, R.; Abel, B.; Esquinazi, P. D.; Meijer, J.; Diziain, S.Cryogenic vector magnet systems make it possible to study the anisotropic magnetic properties of materials without mechanically rotating the sample but by electrically tilting and turning the magnetic field. Vector magnetic fields generated inside superconducting vector magnets are generally measured with three Hall sensors. These three probes must be calibrated over a range of temperatures, and the temperature-dependent calibrations cannot be easily carried out inside an already magnetized superconducting magnet because of remaining magnetic fields. A single magnetometer based on an ensemble of nitrogen vacancy (NV) centers in diamond is proposed to overcome these limitations. The quenching of the photoluminescence intensity emitted by NV centers can determine the field in the remanent state of the solenoids and allows an easy and fast canceling of the residual magnetic field. Once the field is reset to zero, the calibration of this magnetometer can be performed in situ by a single measurement of an optically detected magnetic resonance spectrum. Thereby, these magnetometers do not require any additional temperature-dependent calibrations outside the magnet and offer the possibility to measure vector magnetic fields in three dimensions with a single sensor. Its axial alignment is given by the crystal structure of the diamond host, which increases the accuracy of the field orientation measured with this sensor, compared to the classical arrangement of three Hall sensors. It is foreseeable that the magnetometer described here has the potential to be applied in various fields in the future, such as the characterization of ferromagnetic core solenoids or other magnetic arrangements. © 2020 Author(s).
- ItemMetrological large range magnetic force microscopy(College Park, MD : American Institute of Physics, 2018) Dai, G.; Hu, X.; Sievers, S.; Fernández, Scarioni, A.; Neu, V.; Fluegge, J.; Schumacher, H.W.A new metrological large range magnetic force microscope (Met. LR-MFM) has been developed. In its design, the scanner motion is measured by using three laser interferometers along the x, y, and z axes. Thus, the scanner position and the lift height of the MFM can be accurately and traceably determined with subnanometer accuracy, allowing accurate and traceable MFM measurements. The Met. LR-MFM has a measurement range of 25 mm × 25 mm × 5 mm, larger than conventional MFMs by almost three orders of magnitude. It is capable of measuring samples from the nanoscale to the macroscale, and thus, it has the potential to bridge different magnetic field measurement tools having different spatially resolved scales. Three different measurement strategies referred to as Topo&MFM, MFMXY, and MFMZ have been developed. The Topo&MFM is designed for measuring topography and MFM phase images, similar to conventional MFMs. The MFMXY differs from the Topo&MFM as it does not measure the topography profile of surfaces at the second and successive lines, thus reducing tip wear and saving measurement time. The MFMZ allows the imaging of the stray field in the xz- or yz-planes. A number of measurement examples on a multilayered thin film reference sample made of [Co(0.4 nm)/Pt(0.9 nm)]100 and on a patterned magnetic multilayer [Co(0.4 nm)/Pt(0.9 nm)]10 with stripes with a 9.9 μm line width and 20 μm periodicity are demonstrated, indicating excellent measurement performance.