https://scholars.lib.ntu.edu.tw/handle/123456789/73071
標題: | 軟鐵磁層對垂直異向性FePt/Pt/Cr三層結構之耦合交換力效應探討 Exchange-spring effect of soft Fe top layer onto perpendicular magnetic anisotropy FePt/Pt/Cr trilayer |
作者: | 林季宏 Lin, Ji-Hong |
關鍵字: | 交換耦合;交換彈力;垂直異向性;exchange coupling;exchange spring;perpendicular magnetic anisotropy | 公開日期: | 2006 | 摘要: | 當前水平磁記錄發展已達上限,若要繼續提升記錄密度,必須朝向垂直磁記錄發展,目前製作垂直記錄媒體面臨的困難有:易磁化方向不易在垂直膜面方向、序化溫度過高、矯頑磁力過高等問題,近幾年來前兩項問題已逐漸被克服,但是矯頑磁力過高的問題仍有待解決,因此本實驗藉由改變製程方法來改善上述所說的問題。 本文研究在於利用交換彈力系統的概念,將軟磁層Fe濺鍍在硬磁層FePt(001)薄膜之上,藉由改變濺鍍Fe之溫度、瓦數、厚度,以期許可降低Cr/Pt/FePt/Fe之Hc,進而改善磁頭寫錄的問題。我們並發現濺鍍Fe之溫度與瓦數,並不會對結構或是磁性質有顯著的影響,Fe厚度的改變雖然也不會改變結構,但是對Cr/Pt/FePt/Fe磁性質卻有明顯的變化,當Fe厚度薄時(3、5 nm),在Fe和FePt界面僅有弱的交換耦合力產生,Fe厚度是10 nm時,此時交換耦合力為最強,厚度再增加到15、20 nm時,Hc反而略為上升,同樣的我們量測DCD曲線,也證實了Fe厚度10 nm的確有交換耦合力存在。Cr/Pt/FePt三層結構的垂直方向Hc為2565 Oe,出現最強交換耦合力時,Hc可下降至1312 Oe,這說明了當交換耦合力發生之時Hc可有效降低達50%,這將大幅解決垂直記錄媒體在寫錄時,磁矩不易翻轉的問題。 Nowadays, the areal density of longitudinal magnetic recording reaches their limits. If we keep on upgrading its recording densities, the only way is developing the perpendicular magnetic recording. But, some manufacturing issues of perpendicular magnetic recording need to be solved. For example: tilted easy axis to the film plane, higher soft-hard phase transition temperature, and large writing field of magnetic head to switch the moment of hard phase. In recent years, two problems, tilted easy axis and higher soft-hard phase transition temperature, were solved by epitaxial growth method. However, large writing field of head still confused the researchers. In this investigation, in order to reduce the writing field of magnetic head, we reduced the film coercivity by controlling depositing parameters. The concept of “Exchange Spring” was presented in our study. The film coercivity was largely reduced by capping a soft Fe layer on hard FePt(001) thin films. We found that the microstructures and magnetic properties were not influenced with depositing temperature and sputtering power. The magnetic properties were only affected by Fe layer thickness. When the Fe layer thickness is thinner than 5 nm, weak exchange coupling raised between Fe cap layer and FePt recording layer. When the thickness reached 10 nm, the strongest exchange coupling formed. Film coercivity didn’t distinctly vary as Fe layer thickness is thinner than 15 nm. Consequently, we measured DCD curves and had the same conclusions. Indeed, the appearance of exchange coupling is confirmed with 10 nm Fe cap layer. In our study, out-of-plane coercivity of Cr/Pt/FePt trilayer film is 2565 Oe. When the strongest exchange coupling appears between soft Fe cap layer and hard FePt(001) film, out-of-plane coercivity can be efficiently reduced to about 50%. This will solve the writing problem of perpendicular magnetic recording. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/55150 | 其他識別: | zh-TW |
顯示於: | 材料科學與工程學系 |
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ntu-95-R93527068-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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