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Subject: Magnetic fields × WGL Institute: IOM ×

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Now showing 1 - 2 of 2
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    Magnetic field and angle-dependent photoluminescence of a fiber-coupled nitrogen vacancy rich diamond
    (Melville, NY : American Inst. of Physics, 2021) Wunderlich, Ralf; Staacke, Robert; Knolle, Wolfgang; Abel, Bernd; Meijer, Jan
    Here, we investigate the magnetic field dependent photoluminescence (PL) of a fiber-coupled diamond single crystal with a high density of nitrogen vacancy (NV) centers. Angle-dependent magnetic field sweep measurements between 0 and 111 mT were performed using an oscillating illumination combined with lock-in techniques. Besides the expected superposed PL of differently oriented NV centers, a zoo of features in the PL are found. These features can be associated with level anti-crossings and cross relaxations. In particular, PL measurements allowed us to detect auto-cross relaxation between coupled NV centers. Moreover, the PL measurements at low magnetic fields show dips suggesting an interaction of NV centers with additional spin defects. The results presented here are not only a study for NV-based fiber-coupled sensors made of diamond, but also show a way to investigate with manageable effort and purely an optical multispin interaction with at least one NV center as a constituent.
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    Vectorial 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).