All-optical magnetic imaging with spin defects in van der Waals materials at Angstrom-scale

Magnetic imaging with ultra-high spatial resolution is crucial to exploring the magnetic textures of emerging quantum materials. We propose a novel magnetic imaging protocol that achieves Angstrom-scale resolution by combining spin defects in van der Waals materials and terahertz scattering scanning near-field optical microscopy (THz s-SNOM). Spin defects in the atomic monolayer enable the probe-to-sample distance diving into the Angstrom range where the exchange interactions between the probe and sample spins become predominant. This exchange interaction leads to energy splitting of the probe spin in the order of millielectronvolts, corresponding to THz frequencies. With THz optics and the spin-dependent fluorescence of the probe spin, the interaction energy can be resolved entirely through optical methods. Our proposed all-optical magnetic imaging protocol holds significant promise for investigating magnetic textures in condensed matter physics due to its excellent compatibility and high spatial resolution.