Novel laser-induced dynamics in exchange-biased systemsA. Porat1, S. Bar-Ad1 and I. K. Schuller2
1 School of Physics and Astronomy, Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978, Israel
2 Physics Department, University of California, San Diego - La Jolla, CA 92093-0319, USA
received 26 May 2009; accepted in final form 4 September 2009; published September 2009
published online 1 October 2009
Ultrafast optical excitation of a ferromagnet/antiferromagnet (Ni/FeF2) exchange bias bilayer produces novel magnetization dynamics unlike ever observed before. An unexpected precession of the magnetization, in reverse magnetic fields that exceed the exchange bias, originates from a reorientation of frustrated spins at the interface. As the laser-excited interface approaches the blocking temperature, an exchange bias reversal can also be induced with a single excitation pulse, showing that not only the ferromagnet but also the antiferromagnet is strongly affected by the optical perturbation. This non-trivial response cannot be extrapolated from the known slow dynamics of magnetic bilayers, and provides important information on the physics of the interlayer coupling.
75.70.Cn - Magnetic properties of interfaces (multilayers, superlattices, heterostructures).
75.30.Gw - Magnetic anisotropy.
78.47.jc - Time resolved spectroscopy ( > 1 psec).
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