Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 33: Spin-Dynamics, Magnetization Reversal III

MA 33.13: Vortrag

Donnerstag, 30. März 2006, 18:15–18:30, HSZ 403

Magnetization dynamics in rare-earth orthoferrites — •Carmine Antonio Perroni, Ansgar Liebsch, Andreas Bringer, and Simon Woodford — Institute of Solid State Research (IFF), Research Center Juelich, Juelich 52428, Germany

Recently an ultrafast non-thermal control of magnetization has become feasible in canted antiferromagnets through instantaneous photomagnetic pulses [A.V. Kimel et al., Nature 435, 655 (2005)]. In this experiment circularly polarized femtosecond laser pulses set up a strong magnetic field through the inverse Faraday effect exciting non-thermally the spin dynamics of dysprosium orthoferrites. A theoretical study of magnetization dynamics is performed by using a model for orthoferrites based on a general form of free energy and by solving coupled sublattice Landau-Lifshitz-Gilbert equations. Due to the inverse Faraday effect and the non-thermal excitation, the effect of the laser is simulated analyzing the effect of magnetic field Gaussian pulses on time scales of the order of hundred femtoseconds. As a result, the magnetization oscillates around the initial equilibrium position with amplitudes in agreement with experiment. The simulations are pursued considering the effect of the temperature and of the field pulse along the x-axis in order to excite a different mode as obtained in the experiment. Finally the consequences of a double pump and of a large number of pulses on the magnetization dynamics are analyzed.