AVS 50th International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI-ThA

Invited Paper MI-ThA3
Spatial and Temporal Control of Magnetization Dynamics in Lithographic Elements and Nanocrystalline Composites

Thursday, November 6, 2003, 2:40 pm, Room 316

Session: Magnetization Dynamics
Presenter: M.R. Freeman, University of Alberta, Canada
Authors: M.R. Freeman, University of Alberta, Canada
M. Belov, University of Alberta, Canada
K. Buchanan, University of Alberta, Canada
A. Krichevsky, University of Alberta, Canada
A. Meldrum, University of Alberta, Canada
Correspondent: Click to Email
Time-resolved optical microscopy is a versatile tool for investigations of dynamic phenomena in magnetic thin films, including resonance, reversal, and relaxation.@footnote 1@ Broadband pulsed ferromagnetic resonance studies of square NiFe elements were performed to investigate the control of modal oscillations in inhomogeneously magnetized structures. The spatiotemporal evolution of the magnetization, as excited by a small out-of-plane transient magnetic field, was imaged in the presence of a weak in-plane static bias. In a uniform platelet the spatial response is governed by the nonuniform static magnetization distribution associated with closure domains across the bias field direction. A circular pinhole was patterned in the center of a square platelet to show that the spatial pattern of FMR response also sensitively depends on weak variations of the static magnetization. Comparison to numerical modeling confirms that the experimental observation of spatially-nonuniform damping is a result of the evolution of energy into shorter wavelength modes. The magnetic switching behavior of mesoscopic structures continues to arouse interest for technological applications. Magnetization reversal of mesoscopic structures driven in a crossed-excitation wire (prototype MRAM) geometry will be described. The magnetic and magneto-optical properties of nanocomposite materials created using ion implantation and subsequent thermal processing are also being investigated. Implanting iron ions into a SiO2 host results in a collection of randomly oriented crystalline Fe nanoparticles, the magnetic and microstructual properties of which depend on both the implantation and annealing conditions. Iron implanted SiO2 samples subject to a particular treatment exhibit large Faraday rotation and an extremely fast and tunable response to out-of-plane excitation. @FootnoteText@ @footnote 1@ B.C. Choi, A. Krichevsky, and M.R. Freeman, to be published in Proceedings of the IEEE, June 2003.