銅與氧化銅奈米顆粒複合系統自旋極化參數探討

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/65271

Title:	銅與氧化銅奈米顆粒複合系統自旋極化參數探討
Authors:	陳廷瑋;Chen,Ting-wei
Contributors:	物理學系
Keywords:	自旋極化;銅;氧化銅;奈米顆粒;磁性;電子密度分布;電子分布;塞曼效應;久保能隙;spin polarization;copper;cupric oxide;copper(II) oxide;Cu;CuO;nanoparticle;magnetism;electron density map;Zeeman effect;Kubo gap
Date:	2014-07-18
Issue Date:	2014-10-15 14:48:11 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文探討不同比例，銅與氧化銅奈米顆粒複合系統的磁性參數變化，與樣品的電子密度分布。我們使用熱蒸鍍冷凝法製備銅奈米顆粒，將同一樣品置於空氣中氧化不同天數，由GSAS精算軟體分析，發現銅的氧化物中，僅產生氧化銅。氧化銅重量百分比分別為41 % 與80 %。為了探討兩樣品磁性的變化，進行了一系列磁化強度隨外加磁場變化的實驗，觀察到樣品有自旋極化現象與賽曼效應誘發的磁化強度，使用朗之萬函數與布里淵函數來描述，除此之外還觀察到由氧化銅所貢獻的反鐵磁磁化強度。朗之萬函數的擬合結果為飽和磁化強度隨溫度升高而降低，我們用自旋波激發理論解釋；平均顆粒磁矩隨溫度升高而增強，我們熱磁激發理論解釋。經由氧化銅質量修正反鐵磁磁化率，發現兩樣品中氧化銅在高溫提供的反鐵磁磁化率相當接近。而樣品中分別由銅與氧化銅貢獻的飽和磁化強度與平均顆粒磁矩則為銅貢獻為大。最後使用GSAS軟體，取出樣品中每個材料的電子密度分布。我們發現兩樣品中，銅奈米顆粒的電子分布無明顯改變；而小粒徑氧化銅，銅-氧間的鍵結較大粒徑氧化銅為弱，可能表示小粒徑氧化銅奈米顆粒，銅-氧-銅間的超交互作用較大粒徑氧化銅來得小。 ;In this thesis, we will discuss the magnetism parameters and electron density maps of different proportions Cu/CuO composite system. We were fabricated the copper nanoparticles by thermal evaporation method. To oxidize the sample, we put it in the air during different days. The composition of Cu/CuO is analysis by refining the X-ray diffraction pattern using General Structural Analysis System (GSAS) program. The mass ratios of CuO of two samples are 41 % and 80 %. We did a series of magnetization vary with applied magnetic field experiment, for understand magnetism difference of these samples. From the M(Ha) curve, we find there have three magnetic components. There are come from spin polarization, antiferromagnetism and Zeeman effect induced. We describe the magnetism behavior by Langevin function, linear function and Brilliouin function respectively. From electron density maps, we find there is no obviously difference at copper phase. At CuO phase, we find the Cu-O bonding become weak when particle size reduced. This result may be imply that the superexchange interaction of small size CuO in the Cu-O-Cu bonding is weaker than big size.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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