Theory for Magneto-Optical Detection of the Interfacial Orbital Rashba-Edelstein Effect

Charge-to-orbital conversion via the orbital Rashba–Edelstein effect (OREE) represents a key functionality for orbitronics. In this work, we combine first-principles density functional theory, linear-response theory, and magneto‐optical modeling to reveal how an interfacial OREE can be detected optically through the quadratic magneto-optical Voigt effect in Co/Pt bilayers. We find that, in the Co/Pt bilayer, the current-induced orbital moment can exceed the spin counterpart by nearly a factor of three, underscoring the importance of the OREE. We further show that this orbital moment produces a large current-induced Voigt effect in addition to the equilibrium Voigt effect. Our atom-resolved study reveals that Pt, despite being nominally nonmagnetic, can generate larger Voigt effect than Co, in the presence of the proximity-induced and OREE-induced magnetic moments. The symmetry properties of the Voigt rotations under magnetization reversal show excellent consistency with recent experimental data. These findings establish a pathway for magneto-optical detection of the OREE in magnetic heterostructures.