Regensburg 2002 – wissenschaftliches Programm

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MA: Magnetismus

MA 5: Spindynamik / Ummagnetisierungsvorgänge

MA 5.1: Vortrag

Montag, 11. März 2002, 16:30–16:45, H10

Spin switching in less than a picosecond? — •Ricardo Gómez-Abal, Oleksandr Ney, and Wolfgang Hübner — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120, Halle, Germany

Read/write processes in magnetic storage seem to be reaching their physical limits. Based on recently observed ultrafast spin-dynamics, we adress the possibility of an all-optical ultrafast spin switching by a laser pulse. A simple model employing two-, three-, and four-level systems allows us to explore the requirements of pulse shaping and system characteristics to obtain the simplest possible scenario for spin switching in the subpicosecond regime. Already the two-level system shows the possibility of femtosecond switching, although it is nothing but a manifestation of Rabi oscillations. The three-level system already allows to exploit the role of the quantum phase determining the transition path. Simulation of pump-probe experiments show its role in quantum interference and the distinction between the latter and optical interference. Although we are able to obtain the switching between two ground states, spins are not explicitly involved. The four level system, including the spin explicitly, and spin-orbit coupling for the exchange of angular moment with the orbital one comprises the minimum scenario for an all-optical spin switching within a few femtoseconds. A more sophisticated model describing NiO shows the feasibility of ultrafast spin-switching in this material.