Tunable magnetic field source for magnetic field imaging microscopy

• Published in: Ultramicroscopy 2022-12, Vol.242, p.113624-113624, Article 113624
• Main Authors: Berzins, Andris, Grube, Hugo, Lazda, Reinis, Hannig, Marc A., Smits, Janis, Fescenko, Ilja
• Format: Article
• Language: English
• Subjects: Magnetic field imaging microscopy; Nitrogen–Vacancy centers; Optically detected magnetic resonance; Tunable magnetic field source
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2022.113624

In this work, we present a novel, compact, power efficient and variable magnetic field source design for magnetic field imaging microscopy. The device is based on a pair of diametrically magnetized permanent magnet cylinders with electro-mechanical rotation control and ferrite flux homogenizers. A Hall probe and NV centers in diamond are used to demonstrate a proof of concept of a proposed magnetic field setup and to characterize the homogeneity of the produced magnetic field on a micrometer scale. Numerical simulation results are compared with experimental results showing good agreement of the distribution of the magnetic field in the setup. As a result, a magnetic field source with a tunable field amplitude in the range from 1 mT to 222 mT is demonstrated, achieving a magnetic field homogeneity of 2 ppm/μm or 0.5 μT/μm at 222 mT in a 25 × 25 μm field of view. •A compact, tunable magnetic field source for microscopy applications is presented.•System uses a pair of diametrically magnetized cylinders with ferrite concentrators.•The tuning of the magnetic field is achieved by powering only a stepper motor.•A magnetic field homogeneity of 0.5 μT/μm at 222 mT (2 ppm/μm) is demonstrated.•This system allows fast magnetic hysteresis measurements at a microscale.