Universal Reconstruction of Complex Magnetic Profiles with Minimum Prior Assumptions

Abstract: Understanding the intricate magnetic structures of materials is crucial for the advancements in material science, spintronics, and geology. Recent developments of quantum-enabled magnetometers, such as nitrogen-vacancy (NV) centers in diamond, have enabled direct imaging of magnetic field distributions associated with a wide variety of magnetic profiles. However, reconstructing the magnetization of a sample from a measured magnetic field map poses a complex inverse problem, which can be further complicated by the presence of measurement noise, finite spatial resolution, and the sample-to-sensor distance. While magnetic field distributions are typically measured through various available imaging methods, accurately reconstructing the underlying structures from these maps remains a challenge. In this work, we introduce a novel and efficient GPU-based method for reconstructing magnetic source quantities (i.e. spatially varying magnetization density) from measured magnetic fields with minimum prior assumptions. We validate our method by simulating diverse magnetic structures under realistic experimental conditions, including multi-domain ferromagnetism and magnetic spin textures such as skyrmion, anti-skyrmion, and meron. Experimentally, we apply our technique to investigate the magnetic field maps from a lunar rock (Apollo lunar mare basalt sample 10003,184) obtained using a wide-field quantum diamond microscope. The reconstructed magnetic domains of the lunar rock are consistent with current paleomagnetic knowledge. Our approach provides a versatile and universal tool for investigating complex magnetization profiles, paving the way for future quantum sensing experiments.