Effect of Magnetic Coupling on the Optical Properties of Oxide Co Nanowires on Vicinal Pt Surfaces

Nowadays, modern scientific research has sparked a renewed interest to study the interaction of electromagnetic field (EM) with magnetic nanostructures and in particular in nanophotonics and spintronics. The current work is devoted to an ab initio study of the magneto-optical properties of step-decorated oxide Co nanowires (1D oxides) on vicinal Pt surfaces. Theoretical calculations of the magnetic moments are based on ab initio spin-polarized density-functional theory (DFT) including a self-consistent treatment of spin-orbit coupling. The first-principles calculations revealed the effect of magnetic coupling between cobalt spins on refractivity and extinction spectra of these 1D oxides governed by atomic structure and cobalt-oxygen interaction within a nanowire at the step edge. The emergence of a sharp pronounced peak in the spectral difference of the refractive indexes has been observed between ferromagnetic and antiferromagnetic configurations of the nanowire. Anisotropy of an extinction coefficient in the terahertz (THz) range of the spectra was established for oxide Co nanowires in an antiferromagnetic state in contrast with a ferromagnetic one.