| Summary: | 碩士 === 國立雲林科技大學 === 電子工程與資訊工程技術研究所 === 88 === This dissertation investigates a series of patterned DyFeCo MO samples with perpendicular magnetic anisotropy on the magnetic properties, such as, coercivity, Kerr rotation, and, especially, domain reversal over various depths of hole array barriers. We have used the electron beam lithography techniques to make a various of hole arrays with different depth, such as, 120Å, 750Å and 1700Å, etc.. Then, we coated the Dy21.0(Fe80Co20)79.0 magnetic thin films with thickness 50nm on patterned hole array, and a silicon nitride with 30nm-thick to protect the magnetic thin films. In addition, we have used photo lithography to make a series of larger area samples of square-shaped hole arrays, with 2μm in period and 2μm of width to study the coercivity. Various etched depths, such as, 70 Å, 120Å, 750Å and 1700Å have been fabricated. The observations of micro magnetic domain pinning images for small region samples (under 100μm× 100μm) have been performed using magnetic force microscope, and the hysteresis loops for large region samples (over 1000μm×1000μm) have been measured using a Kerr loop tracer. We found that for the FeCo-rich samples, the coercivity of un-patterned films were always larger than the patterned films, and there was a tendency that coercivity increased as the hole depth increased, excepted that the coercivity of 12nm hole depth was a little be larger than that of 75nm hole depth. On the other hand, for Dy-rich sample of Dy atomic percentage larger than 27 %, the coercivity of un-patterned thin films mostly smaller than the patterned thin films, especially for dysprosium atomic percentage is 27.5% with 12nm hole depth. Finally, we found that for hole depths below 75 nm, the pinning effect due to the hole barriers getting obvious, so far in our experimental, the best pinning effect happened at 7nm hole depth. The measured hysteresis loops also supported this domain pinning effect. A series of sub-micro domain images from various applying magnetic fields and various hysteresis loops will be presented and discussed in this dissertation.
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