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

摘要: 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 Y3Fe5O12$\rm Y_3 Fe_5 O_{12}$ (YIG) is realized with negatively charged boron vacancy (VB−$V_{\rm {B}}^-$) 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 VB−$V_{\rm {B}}^{-}$ is further utilized to study perpendicular magnetic anisotropy (PMA). It effectively extracts the stray field of microwave‐excited magnons from the direct stripline …