UC San Diego

The exploration of novel magnetic materials and spintronic devices is critical for the advancement of next-generation technologies in data storage, sensing, and quantum computing. Understanding the intricate magnetic properties of these materials is essential for both fundamental science and practical applications. Traditional magnetic imaging techniques often fall short in spatial resolution and sensitivity, limiting the ability to probe these properties at the nanoscale. Nitrogen-vacancy (NV) centers in diamonds, however, offer a unique combination of high spatial resolution and exceptional magnetic field sensitivity across a broad temperature range, making them ideal quantum sensors for studying complex magnetic phenomena. This thesis presents the development and application of quantum imaging methods utilizing NV centers to investigate the behavior of novel magnetic materials and spintronic devices. Specifically, we employ NV ensemble-based wide-field imaging techniques to study MBT materials, uncovering detailed insights into their magnetic phases and transitions. Additionally, we explore deterministic magnetic switching in Mn₃Sn devices using both wide-field NV ensemble imaging and high-resolution scanning NV probe techniques. By combining these approaches, we demonstrate the versatility and efficacy of NV-based quantum sensing in probing spintronic phenomena with unprecedented spatial detail. Our experimental results reveal intricate aspects of domain wall dynamics, magnetic switching mechanisms, and emergent magnetic phases that were previously inaccessible with conventional methods. These findings contribute to a deeper understanding of topological magnetic materials and their potential applications in spintronics. This work not only advances the study of novel magnetic materials but also underscores the powerful capabilities of NV centers in diamonds as a quantum sensing platform for investigating emergent magnetic phenomena at the nanoscale.