鈷鈀合金薄膜於藍寶石基板(0001)在氫化效應下對磁性之影響

Hydrogenation Effect on Magnetism of CoPd/Al2O3(0001) thin films

陳昱全(Chen Yu-Chuan)

指導教授 ： 林文欽

國立臺灣師範大學/理學院/物理學系/碩士(2016年)

https://doi.org/10.6345/NTNU202203626

摘要

本論文為探討在室溫下，氫氣吸附與脫離的效應對於不同厚度，10nm、20nm、30nm、60nm Co50Pd50/Al2O3(0001)合金薄膜的影響。
首先樣品皆在超高真空下鍍膜完成，接著使用能量分散X-射線光譜分析(EDX)量測樣品的成分比例，並用穿透式電子顯微鏡(TEM)校正樣品的厚度，然後使用柯爾磁光效應(MOKE)在真空以及曝氫的環境下量測樣品的磁性轉變，最後再使用原子力顯微鏡(AFM)與磁力顯微鏡(MFM)觀察樣品表面與磁區分佈。CoPd的合金在吸附氫氣後，對自身的磁性產生了很大的影響，包括磁滯曲線的矯頑場(Hc)、殘磁(Mr)、飽和磁化量(Ms)與光源反射率等，甚至有磁易軸轉向的情況(Spin Reorientation Transition)，原因就在於Pd能夠吸附比自身體積大很多的氫氣進而擠壓到Co的晶格結構或者因電荷轉移改變合金材料的電子結構。在10nm樣品上，曝氫後矯頑場甚至縮小了7倍之多。隨著厚度不同，每片樣品所表現出的磁性轉變也不同，另外在樣品曝氫時，樣品皆表現出去磁的反應，也就是內部磁區因氫氣吸附而被打亂。藉由重複量測柯爾磁光訊號，發現氫氣的吸附與脫附為可逆反應，反應速度快而且具有重複性。

關鍵字

鈀的氫氣效應 ； 合金薄膜 ； 鈷鈀合金

並列摘要

In this study, we discussed the hydrogenation effect on the magnetic behavior of Co50Pd50/Al2O3(0001) alloy thin films.
The composition of Pd and Co was measured by Energy Dispersive X-ray analysis (EDX). And we use transmission electron microscopy (TEM) to calibrate the thickness of sample. We measured the Megneto-Optical Kerr Effect (MOKE) before and after hydrogen absorption with different thickness of 10nm、20nm、30nm and 60nm alloy thin films. We found there were considerable change in magnetic coercivity (Hc)、magnetic remanence (Mr)、magnetic saturation(Ms) and reflectivity. That's because Pd can absorb a lot of hydrogen atoms in its crystal. The hydrogenation effect might change the crystalline or electronic structure of samples. As the thickness increased, the magnetism of each sample was different. When we exposed the hydrogen in the chamber, the samples became demagnetized. That meant the magnetic domains were reorganized after hydrogen absorption. Besides, we found the hydrogenation effect is reversible and the reaction time is within few seconds to few minutes.

並列關鍵字

palladium hydrogenation effect ； CoPd alloy ； MOKE

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