Visualizing subatomic orbital and spin moments using a scanning transmission electron microscope.

Magnetism originates from the spin and orbital angular momenta of electrons and their coupling. These interactions occur at subatomic scales and a comprehensive understanding of such phenomena relies on characterization techniques capable of probing the spin and orbital moments at atomic resolution. Although electron energy loss magnetic chiral dichroism has previously enabled the detection of magnetic moments at atomic scales, it was limited to a chromatic-aberration-corrected transmission electron microscope. Although possible, the detection of atomic-scale electron energy loss magnetic chiral dichroism in a scanning transmission electron microscope remains elusive due to challenges associated with convergent beam setups. Here we demonstrate the detection of atomic-scale electron energy loss magnetic chiral dichroism signals in a probe-corrected scanning transmission electron microscope. We not only determine the orbital-to-spin moments ratio for individual atomic planes of an iron crystal but also reveal its local variations at subatomic scales. These findings open the possibility of resolving magnetism down to the orbital level in future studies.