Kraus M., Wätzel J., and Berakdar J.

The generation of tightly focused light beams carrying orbital angular momentum (OAM) offers new opportunities for applications in photonics, optoelectronics and optical communications. These spatially inhomogeneous light fields render possible the coupling of the photon field to the angular momentum characteristics of thesample. In this study we exploit this fact and consider nanostructured quantum rings (QRs) irradiated by OAM beams with the aim of inducing swiftly local magnetic moments as well as harmonic generation. Based on a time-dependent quantum simulation we investigate different laser setups for efficient magnetic moment generation during and after the pulse application. In particular, we study the role of the winding number of the optical vortex in enhancing the magnetic moment at a fixed laser intensity. Further, we analyze the emitted radiation associated with the photo-induced charge oscillations and the non-equilibrium current circulation. Irreversible relaxation processes due to the interaction of charged carriers with acoustic phonons are included using a density matrix formalism.

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