鐵與氧化鐵在鎢(111)與鎢(998)上的磁性研究以及鍍率對磁性的影響

在之前的研究裡[1]，將鐵磁性材料如鐵(Iron ; Fe)或鈷(Cobalt ; Co)蒸鍍到單晶的鎢上，利用磁光柯爾效應(MOKE)，發現某些樣品在縱向(in-plane)以及極化方向(perpendicular)上皆可以量測到300~900高斯的矯頑磁場(Coercivity)，並且透過對樣品通以電流時，可以觀察到磁滯曲線(Hysteresis loop)產生很大的偏移(Bias)現象，最大可達150 高斯 / 1安培的偏移量[1]，這種特異的磁性，激發我們很大的興趣。不過由於某些尚未掌握到的關鍵變因，使實驗結果的再現性大有問題。而本研究的動機是找到該關鍵變因，以利後續進一步研究。因歐傑能譜顯示具有特異磁性的薄膜樣品含氧及碳等元素，我們懷疑是雜質導致特異磁性，而進一步猜測也許是氧化鐵在”作怪”。故利用氧化鐵(Fe2O3)當作鍍源來模擬被氧化污染的純鐵，以及與純鐵鍍源交互鍍膜進行實驗，先使用殘氣分析儀(Residual Gas Analyzer)檢查鍍源，並利用歐傑電子能譜儀(Auger Electron Spectroscopic)與低能量電子繞射儀(Low Energy Electron Diffraction)來觀察薄膜的成分以及其表面形貌，再使用程式控溫熱脫附質譜儀(Temperature Programmed Thermal Desorption Spectroscopy)來確定薄膜厚度。對照之前的研究，發現鍍率(Deposition rate)也影響著薄膜的磁性性質，所以本次研究也嘗試著將鍍率當作操作變因來進行實驗。

關鍵字

磁光柯爾效應；矯頑磁場；磁滯曲線；偏移；氧化鐵；鍍率

並列摘要

In the previous study [1], evaporating ferromagnetic material (such as Co and Fe) on the tungsten (111) single crystal which 300~900 gauss coercivity could be measured by the magneto-optical Kerr effect at in-plane and perpendicular direction. Furthermore, by adding current on the sample, the bias phenomenon of the hysteresis loop could be observed [1], with the corresponding magnitude being 30~150 gauss / 1A. However, as we are unable to find out which is the key variable, we cannot successfully repeat the same experimental results. In order to get the large coercivity and hysteresis loop bias on this system, this study is focusing on the situation which the evaporation source is oxidized. We use Iron oxide (Fe2O3) as evaporation source to simulate the condition of pure Iron which is oxidized. Depositing Iron and Iron oxide in turn, we wish to find out whether the phenomenon may be observed. Comparing with previous studies, we found that the deposition rate affects the magnetic properties of the thin films, this study also take this into account as the operating variable.

並列關鍵字

MOKE ； Coercivity ； Hysteresis loop ； Bias ； Iron Oxide ； deposition rate

參考文獻

signal to noise ratio, NSYSU Institutional Repository, Chih-Hsiang Chang, http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search-c/view_etd?URN=etd-0908111-121202

[1] Structure and Magnetism of Co and Fe Films on W(111) Surface, NTNU Institutional Repository, Yi-Chen Lin, http://ir.lib.ntnu.edu.tw/handle/309250000Q/70615

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[2] Current-induced phenomenon on Fe/W(111) and the improvement of

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鐵與氧化鐵在鎢(111)與鎢(998)上的磁性研究以及鍍率對磁性的影響

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