Magneto-optical observation of electrically generated orbital polarization in pristine Cu and oxidized Cu

The electrical generation of orbital angular momentum in materials has attracted significant attention due to its fundamental importance and technological potential. Notably, recent experiments on orbital torque and terahertz emission suggest that Cu enables substantial charge-to-orbital interconversion upon oxidation. However, direct evidence of orbital generation in Cu remains elusive. In this work, we demonstrate current-induced orbital accumulation in pristine and naturally oxidized Cu films