Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 26: Spin Dynamics / Spin -Torque II

MA 26.16: Vortrag

Donnerstag, 28. Februar 2008, 18:30–18:45, EB 301

First-principles study of ultrafast magneto-optical swithing in nickel oxide: Phononic contributions. — •Georgios Lefkidis and Wolfgang Hübner — Dept. of Physics, Kaiserslautern University of Technology, Box 3049, 67653 Kaiserslautern, Germany.

NiO is a good candidate for ultrafast magnetic swiching because of its large spin density, antiferromagnetic order, and clearly separated intragap states. In order to detect and monitor the switching dynamics, we develop a systematic approach to study optical second harmonic generation in NiO, both at the (001) surface and in the bulk [1-2].

We model NiO as a doubly embedded cluster and obtain all intragap d-states of the bulk and the (001) surface with highly correlational quantum chemistry. Then we propagated the states in time under the influence of a static magnetic field and a laser pulse. Switching can be best achieved with linearly polarized light. We also show the importance of including an external magnetic field in order to distinguish spin-up and spin-down states and the necessity of including magnetic-dipole transitions in order to realize the Λ-process in the centrosymmetric bulk [3]. Having already shown the effects of phonons in SHG for the bulk within the frozen phonon approximation [4], we discuss their role as a symmetry-lowering mechanism in the switching scenario and investigate the electronic and lattice temperature effects.
R. Gómez-Abal et al., PRL 92, 227402 (2004)
G. Lefkidis and W. Hübner, PRL 95, 077401 (2005)
G. Lefkidis and W. Hübner, PRB 76, 014418 (2007)
G. Lefkidis and W. Hübner, PRB 74, 155106 (2006)