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研究生: 吳景淼
Wu,Ching Miau
論文名稱: 釔鋇銅氧塊材的磁鬆弛研究
Magnetic relaxation research in the bulk of YBa■Cu■O■
指導教授: 洪姮娥
Horng, Herng-Er
學位類別: 碩士
Master
系所名稱: 物理學系
Department of Physics
畢業學年度: 81
語文別: 中文
論文頁數: 42
中文關鍵詞: 磁鬆弛, 渦流玻璃模型, 釘扎位能
英文關鍵詞: magnetic relaxation , vortex-glass model , pinning potential
論文種類: 學術論文
相關次數: 點閱:250下載:0
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  • 為了了解高溫超導體的磁鬆弛機制, 我們在超導體的混合態中分別做定磁
    場不同溫度及定溫度不同磁場下之磁化率對時間變化的實驗, 實驗結果以
    渦流玻璃模型的解釋最為吻合。以歸一化鬆弛率R'≡M/[M×Ln(t)]分析實
    驗結果,發現不論是定磁場或定溫度, 其R'都大約 成一定值, 範圍在0.02
    至0.05之間, 此結果與 A.P.Malozemoff等人用渦流玻璃模型所得之0.033
    相當。以渦流玻璃模型計算釘扎位能, 在同磁場(3000高斯), 溫度63 K
    以下, 釘扎位能與溫度成正比, 其值從19.5K之33.2meV增加到62.5 K
    之107.1 meV; 而在定溫下(19.5 K), 釘扎位能與所加磁場無關。其值
    從3000高斯至 6000高斯皆約為33 meV。

    In order to realize the mechanism of magnetic relaxation of
    high temperature superconductor, We make magnetization vs time
    experi- ment in mixed state of superconductor with constant
    temperature vs various magnetic field and constant magnetic
    field vs various temperature . The vortex-glass model can
    explain the experiment result well . We analyze the experiment
    result with normalized magnetization R'≡M/[M×Ln(t)] and find
    that R' keeps abount a constant between 0.02 to 0.05 , no
    matter under constant magne- tic field or constant temperature
    . This result approaches the number 0.033 which A. P.
    Malozemoff gets by vortex-glass model. We calculate the pinning
    pontenial by means of vortex-glass mod- el . under same
    magnetic field (3000 Gauss), temperature lower than 63 K , the
    pinning potenial is proportional to temperature. The value
    increases from 33.2 meV (19.5 K) to 107.1 meV (62.5 K). But
    under constant temperature (19.5 K) , the pinning potential has
    no connection with applied field . The value keeps 33 meV from
    3000 Gauss to 6000 Gauss .
    In order to realize the mechanism of magnetic relaxation of

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