藉由RF磁控濺鍍探討鐵磁層溫度變化於鐵酸鉍(BiFeO3)/鐵白金(FePt)雙層磊晶薄膜系統對交換耦合偏壓之影響

Effect of ferromagnetic layer growth temperature on exchange bias of BiFeO3/FePt bi-layer epitaxial films

黃禮駿(Li-Chun Huang)

指導教授 ： 喻冀平 ； 李信義 ； 黃嘉宏

國立清華大學/原子科學院/先進光源科技學位學程/碩士(2014年)

https://doi.org/10.6843/NTHU.2014.00163

摘要

本論文主要目的是探討鉍鐵氧(反鐵磁層)和鐵白金(鐵磁層)雙層磊晶薄膜在鐵磁層不同沉積溫度下對於交換耦合偏壓的影響。在這篇文章中，我們利用高真空雙靶射頻磁控濺鍍系統鍍製我們的雙層薄膜，鉍鐵氧10奈米且鐵白金10奈米，並利用單晶(111)鈦酸鍶基板使薄膜磊晶成長，同時也有系統的研究鐵白金沉積溫度的影響。我們藉由X光繞射及反射圖譜確認磊晶成長的結構，部分的應變鬆弛在磊晶薄膜中垂直方向上可觀察的到。同步輻射X光繞射的結果可以清楚看到鐵白金在500度有明顯的六軸對稱，且用(002)方位角的掃描清楚的指出薄膜是沿著基板排列磊晶成長。在室溫裡改變不同鐵白金成長溫度下可以得到很大的交換耦合偏壓值54-412奧斯特在(111)鉍鐵氧/鐵白金雙層磊晶薄膜中，但是當FePt 溫度超過保存溫度時，交換耦合偏壓值快速的下降。鉍鐵氧表面形貌對於交換耦合偏壓的影響也同時被研究和探討。

關鍵字

薄膜 ； 磊晶 ； 交換耦合偏壓 ； 鉍鐵氧 ； 鐵白金

並列摘要

The objective of the study was to investigate effect of ferromagnetic layer growth temperature on exchange bias of BiFeO3/FePt bi-layer epitaxial films. In this paper, we prepared the BiFeO3 (10 nm) / FePt (10 nm) thin films were epitaxially grown on (111) SrTiO3 (STO) single crystal substrates and systemically study effect of deposition temperature of FePt. The formation of epitaxial films structure was confirmed from the x-ray diffraction and (00L) Bragg reflection of x-ray. A slight partial relaxation of out-of-plane strain in epitaxial systems was observed. Synchrotron radiation XRD results display clear sixfold symmetries and (111) FePt/BiFeO3 films by using (002) azimuthal scan, unambiguously indicating that the present samples were epitaxially thin films. Large exchange field (Heb) of 54－412Oe at room temperature were obtained for the epitaxial (111) BiFeO3 (10 nm) / FePt (10 nm) films at different growth temperatures (300 – 700 ºC). With regard to temperature of FePt, there was a large EB value for the samples with FePt temperature at endpoint. As FePt temperature excesses the blocking temperature, the Heb decreases dramatically. The effect of surface morphology of BiFeO3 layers on Heb in the present samples was also investigated.

並列關鍵字

thin film ； epitaxial ； Exchange bias ； BiFeO3 ； FePt

參考文獻

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