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Student Number 952202005
Author Hsiao-Hui Kuan(管曉慧)
Author's Email Address No Public.
Statistics This thesis had been viewed 1298 times. Download 775 times.
Department Physics
Year 2007
Semester 2
Degree Master
Type of Document Master's Thesis
Language zh-TW.Big5 Chinese
Title Electron transport and magnetoresistivity of In/Co nanoparticle composites
Date of Defense 2008-06-20
Page Count 73
Keyword
  • compacting density
  • coulomb blockade effect
  • Giant magnetoresistance(GMR)
  • Hopping
  • Lorentzian profile fitting
  • magnetoresistance
  • Mott’s three-dimensional variable range hopping
  • Nanoparticle
  • Nanopolymer Composites
  • Ordinary Magnetoresistance( OMR)
  • quantum confinement effect
  • Quantum tunnelling effect
  • resistivity
  • thermal fluctuation
  • Thermal Tvaporator
  • tunneling
  • X-Ray Diffraction System
  • Zeeman effect
  • Abstract Indium nanoparticle was fabricated by thermal evaporation method .Sample purity and diameter were characterized by x-ray diffraction scheme. The analysis result show the pure 16 nm indium nanoparticle were obtained. No trace of impurity and oxidation was found. The result powder was mix with 28 nm cobalt with proper mass ratio, which defined as (In)X(Co)100-X(X=0,50,30,20,10).
    Temperature profile of electric transport properties of all samples were study by DC resistivity system. The measured curves were analysis both by tunneling and Mott’s VHR theory. The fitting result show Mott’s three-dimensional variable range hopping could well describe all resistivity cures, which implies the electric transport were implies three dimensional isotropic.
    The MR ratio of all samples at selective temperature was measured . Positive magnetoresistance (MR) at low applied magnetic fields to a negative MR at high fields were observed in our In/Co nanocomposites.This behavior is originated from Zeeman split of free electron level(ZMR).Two competitions mechanism is suggested .At first , the applied field described the electron levels into parallel and antiparallel the field, which caused lower hopping activation energy of high spin electrons. In the second, the applied field also reduce number of population of such electrons . So that , results positive to negative MR ratio transition.
    Table of Content 論文摘要.......................Ⅰ
    Abstract.......................Ⅱ
    致謝............................Ⅲ
    目錄............................Ⅳ
    圖目............................Ⅵ
    表目............................Ⅹ
    第一章 序論
    1-1  金屬奈米顆粒的紹 ...............................1
    1-2  複合奈米材料的導電特性..........................5
    1-3  實驗動機........................................7
    第二章 樣品備製與實驗儀器簡介
    2-1  銦奈米顆粒的製備方法-熱蒸鍍低真空冷凝製程.......8
    2-2  X光繞射儀......................................10
    2-3  粒徑分析 ......................................12
    2-4  複合奈米樣品製作 ..............................16
    2-5  電阻實驗儀器與量測 ............................23
    第三章 電阻與磁阻機制
    3-1  電子跳躍式與穿隧式傳導.........................26
    3-2  磁阻的定義與種類 ..............................33
    3-3  穿隧性磁阻TMR..................................38
    3-4  塞曼效應(Zeeman effect)之磁阻ZMR..............39
    第四章 電阻實驗分析與物理意義探討
    4-1  電阻率隨溫度量測結果與分析.....................42
    4-2  不同成分造成電阻率的變化.......................49
    4-3  複合材料的超導現象.............................53
    第五章磁阻實驗結果與物理意義探討
    5-1  磁阻率與溫度關係...............................55
    5-2  磁阻率隨聚合密度的變...........................58
    5-3  磁阻率與磁化強度的關...........................62
    5-4  磁阻率與Zeeman效應 ............................66
    5-5  熱擾動導致磁阻率異常現象.......................67
    第六章  結論........................................70
    參考文獻.............................................72
    Reference 參考文獻資料:
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    [2]楊仲準,鐠系與鉍系龐磁阻材料結構、電性、磁性間的互動關係研究,中央大學博士(2004)
    [3] Electronic Processes in non-crystalline Material, Mott. and Davi.
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    Petroff, Phys. Rev. Lett. 61 2472(1988)
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    [7]F. Petroff, A. Barthelemy, D. H. Mosca, D. K. Lottis, A. Fert, P. A. Schroeder, W. P. Pratt, Jr. R. Loloee and S. Lequien, Phys. Rev. B44, 5355(1991)
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    [11]Introduction to Solid State Physics, KITTEL
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    [13] Richard W. Robinett, Quantum Mechanics,p262
    [14] David Bohm, Quantum Theory,p286
    Advisor
  • Wen-Hsien Li(李文献)
  • Files
  • 952202005.pdf
  • approve immediately
    Date of Submission 2008-06-23

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