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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/17741

Title: 奈米線寬鎳鐵橢圓環磁矩翻轉隨長寬比之變化與陣列中距離的影響
Variation of magnetization reversal in nanometer wide NiFe elliptical rings with various aspect ratios and with inter-unit distance
Authors: Kuan-Yu Chen
陳冠瑜
Contributors: NTOU:Institute of Optoelectronic Sciences
國立臺灣海洋大學:光電科學研究所
Keywords: 磁光科爾效應;鎳鐵橢圓環;形狀異向性;磁交互作用
MOKE;oval ring;shape anisitropy;magnetic interaction
Date: 2009
Issue Date: 2011-07-04
Abstract: 本論文主要研究為奈米線寬鎳鐵橢圓環磁矩翻轉隨長寬比之變化與陣列中距離的影響,主要是利用縱向磁光科爾效應儀(MOKE)、微磁學模擬系統(OOMMF)來進行實驗與分析。透過本實驗室自行架設的磁光科爾效應儀(MOKE)來量測線寬最小可達100nm的鎳鐵橢圓環的磁滯曲線,利用固定橢圓環中心周長為6.3μm,改變橢圓環長軸與短軸之比,來研究當固定線寬,改變橢圓環的長寬比與膜厚,對磁化過程中磁矩翻轉的影響。由實驗結果發現,當橢圓環長寬比越小、膜厚越厚,在磁化翻轉中越容易產生磁化暫穩態,即渦漩態(vortex state)的產生,而讓橢圓環在翻轉過程中產生二階翻轉的現象(洋蔥態 onion state→渦漩態 vortex state→onion state)。 MOKE是光學量測系統,光點可以縮小到直徑為5~50μm的大小,但當樣品縮小到奈米尺度時,為了增加訊號的強度,我們會將樣品設計成陣列。在量測鎳鐵橢圓環陣列時,環與環之間的磁交互作用是影響橢圓環陣列磁化翻轉的重要因素。從文獻中可以知道,當環與環之間的距離越近,磁交互作用的影響越大,主要影響的原因為當有漏磁場(stray field)產生時,漏磁場會影響到鄰近橢圓環的磁化翻轉。本論文利用將鎳鐵橢圓環交錯排列,並以「行」為單位從外往內靠攏,以研究當陣列交錯排列時,行間距對陣列磁化翻轉的影響。
We have studied variation of magnetization reversal in nanometer wide single layer NiFe elliptical rings with various aspect ratios and with different inter-unit distance, using longitudinal magneto-optical Kerr effect magnetometer (L-MOKE) and micro-magnetic simulation (OOMMF). Our home-made L-MOKE is capable of measuring the hysteresis loops of 100nm wide samples. We kept the circumferences of the elliptical rings around 6.3 μm but changed the length of long axis and short axis. The magnetization reversal of NiFe elliptical rings as functions of the film thickness and aspect ratio was investigated in detail. According to our experiment, the flux-closure vortex state was found in thick films and small aspect ratios. The two-step switching behavior occurred in these elliptical rings (onion state→vortex state→onion state). MOKE is an optical measurement system and the spot size of laser is 5~50μm. When the sample size was varied down to nanometer scale, we used arrays of elliptical rings to increase the signal-to-noise ratio. In arrays of elliptical rings, the magnetostatic interaction influenced the magnetization reversal. In the previous research, when the distance between circular rings was reduced, the magnetostatic interaction would be very strong due to the stray field. In this part of the thesis, we changed the distance by a shifted arrangement for every other rows in the short axis direction. The position was fixed in the short axis direction and the distance in the long axis direction was changed to investigate the magnetostatic interaction.
URI: http://ethesys.lib.ntou.edu.tw/cdrfb3/record/#G0M96880018
http://ntour.ntou.edu.tw/ir/handle/987654321/17741
Appears in Collections:[光電科學研究所] 博碩士論文

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