2005/07/20 by M. C. Weber, Marius Weber, Hans T. Nembach +8
Engineering · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Magnetic Properties and Applications #Magnetic properties of thin films #Magneto-Optical Properties and Applications #Materials Science (cond-mat.mtrl-sci) #cond-mat.mtrl-sci
paper · pdf · doi:10.48550/arxiv.cond-mat/0507475
28 pages, 7 figures
arxiv created 2005/07/20 · openalex publication_date 2005/07/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
An internal anisotropy pulse field is launched by an 8.3 ps short laser excitation, which triggers precessional magnetization dynamics of a polycrystalline NiFe/FeMn exchange bias system on the picosecond timescale. Due to the excitation the unidirectional anisotropy and, thus, the exchange coupling across the interface between the ferromagnetic and the antiferromagnetic layer is reduced, leading to a fast reduction of the exchange bias field and to a dramatic increase of the zero-field susceptibility. The fast optical unpinning is followed by a slower recovery of the interfacial exchange coupling dominated by spin-lattice and heat flow relaxation with a time constant of the order of 160 ps. The measured picosecond time evolution of the exchange decoupling and restoration is interpreted as an anisotropy pulse field giving rise to fast precessional magnetization dynamics of the ferromagnetic layer. The strength of the internal pulse field and even the initial magnetization deflection direction from the equilibrium orientation can be controlled by the absorbed photons. The dependence of the effective Gilbert damping on both small and large angle precessional motion was studied, yielding that both cases can be modeled with reasonable accuracy within the Landau-Lifshitz and Gilbert framework.