| Summary: | 碩士 === 國立彰化師範大學 === 光電科技研究所 === 100 === Patterned magnetic thin films have been widely investigated for developing spintronic devices. One of the most important issues is the morphology of the element by which the shape anisotropy is introduced to influence the behaviors of magnetization reversal. Herein, we report a study focused on size dependent magnetization reversal properties in an array of cascaded magnetic ellipses. The permalloy ellipses in series were fabricated by a standard electron beam lithography through an lift-off process. The pattern dimensions are as follows: short axis is fixed with 100 nm and three segments in long axes are 300, 600, 300 nm, respectively. The film thickness is controlled to be 10 and 15 nm. The magnetization reversal processes of these permalloy thin film ellipses were investigated by using Magneto-Optical Kerr Effect (MOKE) measurements and Magnetic Force Microscopy (MFM). Notice that the external magnetic field direction is varied with respect to the long axis (field angle). The switching behaviors are interpreted with the experimental data in conjunction with a simulation using OOMMF software. It is found that the squareness degrades with increasing the field angle. In addition, it is observed that different magnetization reversals reveal at certain field angles, 45 and 75 degrees, based on OOMMF simulations and MFM results.
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