核殼結構的奈米Cu/Cu2O微粒之自旋極化與弱鐵磁現象; The spin polarization and weak ferromagnetism in core-shell Cu/Cu2O nanoparticles.

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/7519

Title:	核殼結構的奈米Cu/Cu2O微粒之自旋極化與弱鐵磁現象;The spin polarization and weak ferromagnetism in core-shell Cu/Cu2O nanoparticles.
Authors:	傅喬玟;Chiau-Wen Fu
Contributors:	物理研究所
Keywords:	自旋極化;spin polarization
Date:	2007-06-20
Issue Date:	2009-09-22 10:59:15 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本實驗採用熱蒸鍍法製備數組Cu 奈米微粒，經過氧化後形成 Cu/Cu2O 奈米微粒，最後採用三組樣品粒徑分別為3.4 nm、2.3 nm 與3.9 nm。並使用物理特性量測系統(Physical property measurement system)量測其磁性，利用朗之萬函數(Langevin function)加上一線性項擬合實驗，此線性項為順磁與反磁一起貢獻的結果，進而分析其磁性。在塊材的銅與氧化亞銅皆為反磁性，但此實驗發現在低磁場部分由鐵磁性表現，高磁場則為銅與氧化亞銅共同表現的現象，當溫度升高時反磁現象越明顯，不過當Cu2O 變多時反而是使反磁性降低。由此也可推測出核內的銅在奈米尺度下能為反磁性，但氧化亞銅則與塊材實的磁性有所不同。在磁矩與溫度的關係上，則發現磁矩排列隨溫度上升而變大的特性，μP ~ kBT。而造成這些與塊材磁性相異的原因，推測乃因表面電子自旋極化與Cu/Cu2O 部分氧缺陷所造成。 Copper nanoparticles were fabricated by the thermal evaporation method. A series of copper nanoparticles were oxided to form core-shell structure. The diameters of 3.4 nm, 2.3 nm and 3.9 nm Cu/Cu2O nanoparticles were determined by atomic force microscope images. We observe the spin polarization in Cu/Cu2O fine particles. The applied magnetic field dependency of magnetization (M-H curve) can be described by using Langevin function. And we also find two magnetic components in Cu/Cu2O nanoparticles at low temperatures. We can find that the fitting parameters μp increase with increasing temperature. According to ferromagnetic component in M-H curves and remanence, the ferromagnetic spin polarization of Cu/Cu2O nanoparticles is observed.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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