Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 13: Poster:Schichten(1-23),Spinabh.Trsp(24-41),Exch.Bias(42-56),Spindyn.(57-67),Mikromag.(68-76),Partikel(77-90),Spinelektr.(91-97),Elektr.Theo.(98-99),Mikromag+PhasÜ+Aniso.(100-105),Magn.Mat.(106-118),Messmethod.(119-121),Obflm.+Abbverf.(122-123)

MA 13.67: Poster

Dienstag, 9. März 2004, 15:00–19:00, Bereich A

Ultrafast Magnetization Dynamics in Antiferromagnets — •N.P. Duong¹, T. Satoh^1,2, 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 153-8904 Japan

The dynamic behavior of antiferromagnets is expected to be substantially different from that of ferromagnets. Magnetic switching is facilitated by the absence of a macroscopic magnetic moment, and reversal of the antiferromagnetic order parameter within ∼ 10 fs was predicted. Over the last decade the demagnetization behavior of many ferromagnetic compounds and heterostructures has been studied. However, the spin dynamics of antiferromagnets remains largely unknown. Here we report investigation of antiferromagnetic Cr₂O₃, NiO, and RMnO₃ (R=Y, Ho) by optical pump-and-probe experiments. Magnetic second harmonic generation (SHG) is used as probe of the antiferromagnetic order. Comparison to crystallographic SHG and optical transmission and reflection allows us to distinguish between the dynamics of the magnetic and nonmagnetic sublattices. All three components exhibit temporal evolution of the magnetic and crystallographic contributions on independent time scales, thus indicating weak spin-lattice interaction. In NiO an oscillation of the magnetic moment after the excitation is observed. In Cr₂O₃ different temporal behavior of amplitude and phase of the magnetic signal is demonstrated. In the hexagonal manganites the temporal evolution of a magnetic phase transition is revealed.