E. W. Lee

Bio: E. W. Lee is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 13 citations.

Thin Ferromagnetic Films

Abstract: Thin Ferromagnetic Films By M. Prutton. Pp. viii + 269. (London: Butterworth and Co. (Publishers), Ltd., 1964.) 80s.

Optoelectronic integration using the magnetically assisted statistical assembly technique : initial magnetic characterization and process development

Abstract: The commercial integration of optoelectronic devices heavily relies on hybrid techniques such as wire bonding and flip-chip bonding. These methods are limited in the scale and flexibility in integration. Research focused on optoelectronic integration is performed using numerous techniques such as direct epitaxy, full-scale wafer bonding, and selfassembly. Magnetically Assisted Statistical Assembly (MASA) is an example of the latter technique and improves scale and flexibility by enabling the simultaneous integration of large numbers of individual devices. This thesis work is focused on the demonstration of the MASA concept through characterization of the magnetic materials forming the foundation for this technique and development of an adequate process technology. Both, the magnetic characteristics and the process technology required to integrate the technology are presented along with results of the integration. Thesis Supervisor: Clifton G. Fonstad Jr. Title: Professor of Electrical Engineering

Oxygen Incorporation into Electrodeposited CoFe Films: Consequences for Structure and Magnetic Properties

Abstract: The nanostructure and magnetic properties of electrodeposited Co40Fe60 alloy films containing varying amounts of oxygen were investigated using transmission electron microscopy (TEM) and diffraction, secondary ion mass spectroscopy (SIMS), and superconducting quantum interference device (SQUID) measurements. Oxygen content in the CoFe deposit was controlled by electrolyte composition. Films were deposited on Si {100} substrates with thin Cu/Ti seed layer. Electron energy loss and x-ray spectroscopies showed that the low oxygen films contained intragranular FeO particles and that the high oxygen films contained Fe2O3 along grain boundaries. The films with oxide present at the grain boundary had increased coercivity and reduced saturation magnetization relative to the lower oxygen content films with intragranular oxide. The differences in magnetic properties between low oxygen and high oxygen concentration films were attributed to stronger mobile domain wall interactions with the grain boundary oxide layers relative to interactions with the intragranular oxide particles in the low oxygen specimens.

Barkhausen noise in magnetic thin films

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Continuum limit and stochastic homogenization of discrete ferromagnetic thin films

Abstract: We study the discrete-to-continuum limit of ferromagnetic spin systems when the lattice spacing tends to zero. We assume that the atoms are part of a (maybe) non-periodic lattice close to a flat set in a lower dimensional space, typically a plate in three dimensions. Scaling the particle positions by a small parameter $\varepsilon>0$ we perform a $\Gamma$-convergence analysis of properly rescaled interfacial-type energies. We show that, up to subsequences, the energies converge to a surface integral defined on partitions of the flat space. In the second part of the paper we address the issue of stochastic homogenization in the case of random stationary lattices. A finer dependence of the homogenized energy on the average thickness of the random lattice is analyzed for an example of magnetic thin system obtained by a random deposition mechanism.

Permalloy multilayers to reduce the effects of uniaxial anisotropy

Abstract: The anisotropic magnetoresistance effect of Permalloy (Ni/sub 0.82/Fe/sub 0.18/) is used in a contactless angle detector. The uniaxial magnetic anisotropy in a Permalloy thin film causes a difference between the direction of magnetization and the magnetic field direction. This leads to a systematic error in the angle detector output. The effects of uniaxial magnetic anisotropy can be reduced by using Permalloy multilayers with different orientations of their anisotropy axes. A double layer with mutually perpendicular anisotropy axes is found to be sufficient for application in an angle detector. The Stoner-Wohlfarth single-domain model is used to describe the systematic error of an angle detector using multilayers. >