錫鎳奈米核殼結構的法拉第磁感應探討

Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/71662

Title:	錫鎳奈米核殼結構的法拉第磁感應探討
Authors:	李鎮宇;Lee,Chen-Yu
Contributors:	物理學系
Keywords:	錫鎳奈米;法拉第磁感應;磁性鬆弛;弛豫現象
Date:	2016-07-05
Issue Date:	2016-10-13 13:28:43 (UTC+8)
Publisher:	國立中央大學
Abstract:	本篇論文討論 Sn@Ni 核殼結構奈米顆粒的磁性、超導研究與磁性鬆弛行為，使用熱蒸鍍冷凝法的雙鍍源方式製作本樣品，經由 X 光繞射譜圖、EDXS與 TEM判定 Sn核直徑為2.4 nm，Ni殼的厚度為 1.9 nm。 Sn@Ni 在外加磁場 Ha = 200 Oe 的阻擋溫度 TB = 43 K，；Ha = 1 kOe ，TB = 6 K；Ha = 5 kOe，TB = 2.4 K。對其做磁化率隨著溫度變化的實驗，可發現 Sn@Ni 具有弱自旋玻璃行為與超導臨界磁場 Hc0 = 2.9 kOe。 Sn@Ni 奈米顆粒磁性鬆弛研究具有磁化強度翻轉的行為，此行為可得知與本樣品為核殼結構有關。磁化強度隨時間鬆弛的曲線，應有兩個分量的貢獻，分別是殘留的磁化強度 Mr 曲線和感應的磁化強度 Mi曲線。弛豫現象與溫度、外加磁場、降場速率有關。最後將 Sn@Ni 與本實驗室的 Au@Ni 做個比較，可得知 Sn@Ni 感應的磁化強度百分比 Pi0比 Au@Ni 的來的強。;We report on the magnetic properties, superconductivity and magnetic relaxation behaviors in the nano-sized Sn@Ni core@shell particles. The Sn@Ni NPs were fabricated employing the gas-condensation method, using a chamber equipped with two decoupled evaporation sources for separate evaporation of Sn or Ni. We use X-ray diffraction pattern, energy-dispersive X-ray spectroscopy and transmission electron microscopy, resulting in a mean particle core diameter of 2.4 nm and shell thickness of 1.9 nm. In applied magnetic field Ha = 200 Oe, the blocking temperature TB of Sn@Ni is 43 K; Ha = 1 kOe, TB = 6 K; Ha = 5 kOe, TB = 2.4 K. Doing χ(T) experiment, Sn@Ni has weak spin glass behavior and the critical magnetic field Hc0 = 2.9 kOe. The study of magnetic relaxation behaviors of Sn@Ni NPs had inverse magnetization behavior. It related to core@shell structure and it depended on temperature, applied magnetic field, and turning the Ha off. M(t) should have two components: remanent magnetization Mr and Faraday inductive magnetization Mi. At last, we made a comparison between Sn@Ni and Au@Ni. The ratio of Faraday inductive magnetization Pi0 of Sn@Ni had much stronger than Au@Ni.
Appears in Collections:	[Graduate Institute of Physics] Electronic Thesis & Dissertation

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