Regensburg 2000 – wissenschaftliches Programm

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AM: Magnetismus

AM 22: Spektroskopie II

AM 22.1: Vortrag

Donnerstag, 30. März 2000, 14:30–14:45, H22

Nonlocal theory of nonlinear magneto-optics — •Torsten Andersen and Wolfgang Hübner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D–06120 Halle/Saale

We present a nonlocal model that describes optical second-order processes in magnetic media of mesoscopic size, with emphasis on sum- and difference-frequency generation and the nonlinear magneto-optical Kerr effect. Nonlocality plays a role in surface and interface optics, since the transition from one medium to another cannot be described neither by a sharp boundary, nor by a slowly varying envelope. Our theory employs a density matrix formalism with the interaction Hamiltonian for the vector potential taken in the weakly relativistic limit. The optical properties are calculated self-consistently, but as a perturbation to the ground state of the material involved, and the ground state is assumed to be spin-polarized and include the appropriate spin-orbit coupling term. The ground-state properties necessary as input for getting numerical results from our theory are the wavefunctions, eigenenergies, and the chemical potential (possibly the Fermi energy) of the material system. The theory enables us also to calculate collective excitations and the diamagnetic contributions, and we are able to treat different nonlinear processes in a unified frame on equal footing.