Berlin 2005 – scientific programme

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MA: Magnetismus

MA 8: Spindynamik I

MA 8.2: Talk

Friday, March 4, 2005, 15:30–15:45, TU H1028

Phase-sensitive Ultrafast Spin Dynamics in Antiferromagnetic Cr₂O₃ — •T. Satoh^1,2, B.B. van Aken¹, N.P. Duong¹, Th. Lottermoser¹, and M. Fiebig¹ — ¹Max-Born-Institut, Max-Born-Straße 2A, 12489 Berlin — ²RCAST, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo

With the discovery of magnetization processes on the (sub-) ps time scale the coupling processes between spins, electrons and lattice that allow such rapid manipulation of the magnetic order parameter became a central topic. Here we discuss the temporal evolution of spin and charge lattices in antiferromagnetic Cr₂O₃ upon excitation with an intense 100 fs laser pulse. Optical second harmonic generation (SHG) is used as probe for the magnetic and crystallographic sublattices, since linear magnetooptical techniques fail because of the absence of a macroscopic magnetization. By coherent interference of the magnetic and crystallographic contributions to SHG the temporal evolution of both amplitudes and phases of the magnetically induced signal can be observed. The dynamical response of Cr₂O₃ occurs on three different time scales (∼ 1 ps, ∼ 10 ps, ∼ 1 ns). The result indicate weak spin-lattice coupling in the absence of the pump light field and a different temporal evolution of the amplitude and the phase of the magnetic signal. Possible relations to the magnetoelectric behavior of Cr₂O₃ are discussed.