Browsing by Author "Pechan, MJ"

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    Dipolar induced, spatially localized resonance in magnetic antidot arrays
    (American Institute of Physics, 2003-11-03) Yu, CT; Pechan, MJ; Mankey, GJ; University System of Ohio; Miami University; University of Alabama Tuscaloosa
    Dipole induced, spatially localized ferromagnetic resonances (at 35 GHz) are observed in micron-sized antidot arrays in permalloy films fabricated with photolithography. All square (3 mum x 3 mum) and rectangular (3 mum x 4, 5, and 7 mum) array samples exhibit double resonances, with each resonance possessing uniaxial in-plane anisotropy. Interestingly, the easy axes of the two resonances are orthogonal in all cases. The magnitude of the induced dipolar anisotropy decreases with increasing rectangular aspect ratio for one of the resonances, but remains essentially constant for the other. Micromagnetic simulations reveal that the two resonance peaks are the consequence of a dipole field distribution producing two areas with distinctly different demagnetizing field patterns. (C) 2003 American Institute of Physics.
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    Lateral standing spin waves in permalloy antidot arrays
    (American Institute of Physics, 2004-05-25) Yu, CT; Pechan, MJ; Burgei, WA; Mankey, GJ; University System of Ohio; Miami University; University of Alabama Tuscaloosa
    Spin wave modes in permalloy antidot arrays have been investigated with ferromagnetic resonance at 9.7 GHz. In contrast to a quadratic dispersion expected for exchange standing spin waves, nearly linear relationship exists between the resonance field and mode index, and it can be approximately described by the dipole-dipole and exchange theory. Time-dependent micromagnetic simulations show that the spin wave modes are a result of lateral confinement from the vacant holes. Furthermore, the simulations visually reveal the existence of localized spin waves due to localized boundary conditions in antidots arrays. (C) 2004 American Institute of Physics.
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    Magnetic properties of uniaxial synthetic antiferromagnets for spin-valve applications
    (American Physical Society, 2005-03-25) Zhao, ZY; Mani, P; Mankey, GJ; Gubbiotti, G; Tacchi, S; Spizzo, F; Lee, WT; Yu, CT; Pechan, MJ; Consiglio Nazionale delle Ricerche (CNR); Istituto Nazionale per la Fisica della Materia (INFM-CNR); Sapienza University Rome; University of Perugia; University of Ferrara; United States Department of Energy (DOE); Oak Ridge National Laboratory; Spallation Neutron Source; University System of Ohio; Miami University; University of Alabama Tuscaloosa
    The magnetic properties of synthetic antiferromagnetic Si(100)/Ta (5 nm)/Co(t(1))/Ru (0.65 nm)/Co(t(2))/Ta (10 nm) with an obliquely sputtered Ta underlayer are reported as a function of the top Co layer thickness, t(2). The morphological origin of the large in-plane magnetic anisotropy created by the obliquely sputtered Ta underlayer is revealed by atomic force microscopy. The magnetic anisotropy of the base Co layer is determined by measuring the dispersion of the Damon-Eshbach spin-wave mode with Brillouin light scattering. Ferromagnetic resonance measurements and hysteresis loops reveal that both the anisotropy and the saturation field of the trilayer system decrease with increasing top Co layer thickness. The dependence of the saturation field on layer thickness is fitted to an energy minimization equation that contains both bilinear and biquadratic exchange coupling constants. Magnetoresistance and polarized neutron reflectometry results both confirm that the magnetic reversal process of the system is through magnetic domain formation followed by rotation.