2008/05/22 by J. Walowski, J Walowski, M. Djordjevic Kaufmann +9 · 172 citations
Engineering · Materials Science · Physics and Astronomy · #Crystallite #Dysprosium #Femtosecond #Laser #Laser Material Processing Techniques #Magnetic Properties and Applications #Magnetic damping #Magnetic properties of thin films #Magnetization dynamics #Nickel #Permalloy #Spin wave #cond-mat.other
paper · pdf · doi:10.1088/0022-3727/41/16/164016
published in Journal of Physics D Applied Physics 41(16), 164016 (Institute of Physics)
arxiv created 2008/05/22 · openalex publication_date 2008/08/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
The use of femtosecond laser pulses generated by a Ti : sapphire laser system allows us to gain an insight into the magnetization dynamics on time scales from sub-picosecond up to 1 ns directly in the time domain. This experimental technique is used to excite a polycrystalline nickel (Ni) film optically and probe the dynamics afterwards. Different spin-wave modes (the Kittel mode, perpendicular standing spin-wave modes and dipolar spin-wave modes (Damon–Eshbach modes)) are identified as the Ni thickness is increased. The Kittel mode allows determination of the Gilbert damping parameter α extracted from the magnetization relaxation time τ α . The non-local damping by spin currents emitted into a non-magnetic metallic layer of vanadium (V), palladium (Pd) and the rare earth dysprosium (Dy) are studied for wedge-shaped Ni films of 1–30 nm. The damping parameter increases from α = 0.045 intrinsic for nickel to α > 0.10 for the heavy materials, such as Pd and Dy, for the thinnest Ni films below 10 nm thickness. Also, for the thinnest reference Ni film thickness, an increased magnetic damping below 4 nm is observed. The origin of this increase is discussed within the framework of line broadening by locally different precessional frequencies within the laser spot region.