Development of a compact magnet for applying a highly uniform magnetic field to a diamond magnetic sensor by inverse problem analysis

We propose a novel method based on the inverse problem approach to optimize the shape of a magnet generates high uniformity of magnetic fields in a magnetometer with diamond nitrogen-vacancy (NV) centers. Our original method can determine the combination of magnetic moments required to design a unique magnet shape. We obtained a unique shape of the small magnet (optimized model, 15 × 15 × 25 mm3 and 25 × 25 × 15 mm3) for integrated magnetometry system and improved the magnetic uniformity from 83.6% to 99.0% in the diamond NV centers area (X = -1-1 mm, Y = -1-1 mm, Z = 5-6 mm). The results indicate a highly sensitive magnetometer with a diamond NV center for future biomedical applications.