First-Principles Calculation of the Optical Response of Current-Driven Orbital Magnetization

In this work we present a theoretical investigation of the current-induced optical response in metallic systems with locally broken inversion symmetry. Within the framework of linear response, we study the impact of bias currents on the optical absorption, separating them into two distinct components: Fermi surface effects associated with extrinsic scattering mechanisms and Fermi sea effects linked to intrinsic scattering processes. Employing ab-initio methods, we comprehensively compute the tensor elements of the optical response induced by current in a Pt slab structure. Our analysis reveals that the extrinsic component can lead to circularly polarized light absorption. When integrated across all frequencies, this response is related to the optically active component of the current-induced orbital magnetization. Decomposing the optical response tensor elements on each layer we show that the two surfaces of Pt slab have opposite contribution to the current induced orbital accumulation, which originates from the presence of the Rashba effect at the surface, and signifies the necessity for locally broken inversion symmetry in the system.