Detecting and Imaging of Magnons at Nanoscale with van der Waals Quantum Sensor

Abstract Magnonic devices are extensively studied for energy‐efficient information processing. High spatial resolution and high accuracy measurement is required to characterize the excitation and distribution of magnons. Here, sensing and imaging of magnons in the magnetic insulator (YIG) is realized with negatively charged boron vacancy () spin defects in 2D hexagonal boron nitride (hBN). Thermal magnon noise is studied through spin relaxometry, illustrating the nanometers proximity of the 2D quantum sensor over a large area. The small probe‐sample standoff distance helps to detect weak signals with diffraction‐limited spatial resolution. The uniform out‐of‐plane symmetry axis of is further utilized to study perpendicular magnetic anisotropy (PMA). It effectively extracts the stray field of microwave‐excited magnons from the direct stripline field. The distributions of propagating and localized magnons in different structures are subsequently imaged and analyzed. The work provides the strategy for utilizing the distinctive advantages of the van der Waals quantum sensor in magnetic imaging. The results will promote the development of magnonic devices for diverse applications.