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