跳到主要內容

臺灣博碩士論文加值系統

(18.97.9.172) 您好!臺灣時間:2025/02/11 13:03
字體大小: 字級放大   字級縮小   預設字形  
回查詢結果 :::

詳目顯示

我願授權國圖
: 
twitterline
研究生:郭良吉
研究生(外文):Liang-Chi Kuo
論文名稱:半填滿的S能帶的鐵磁不穩定性研究
論文名稱(外文):Ferromagnetic Instability in an Almost Hall-filled s-band
指導教授:黃偉能
指導教授(外文):Wei-Neng Huang
學位類別:碩士
校院名稱:中原大學
系所名稱:應用物理研究所
學門:自然科學學門
學類:物理學類
論文種類:學術論文
論文出版年:2002
畢業學年度:90
語文別:中文
論文頁數:57
中文關鍵詞:單重態哈柏模型鐵磁態
外文關鍵詞:ferromagnetic stateHubbard modelsinglet state
相關次數:
  • 被引用被引用:0
  • 點閱點閱:136
  • 評分評分:
  • 下載下載:6
  • 收藏至我的研究室書目清單書目收藏:0
摘要
  當單一電洞的鐵磁態(ferromagnetic state)系統為基態被證實後,學者便朝兩個電洞的鐵磁態系統前進。由於兩個電洞的鐵磁態系統能量是否為最低的問題,直至現今仍爭議不斷,而眾多學者持續為自己所支持的論點提出研究的成果,不同的計算方式以及近似方法也相繼成現在世人面前,但始終無一結果可讓兩方的支持者同時接受。
本文利用在1963年被提出的哈柏模型(Hubbard model)進行計算,此模型將個電子的能帶緊縮,使之不與鄰近的電子有交互作用,此方式即稱為能帶緊束法(Tight binding method for energy bands)﹔整個模型則是電子移動後所獲得的能量t(t<0 )與庫倫位能U這兩項的影響與限制,且電子只能移動到最鄰近的位置上,而計算的時所考慮的限制條件則是電子移動時不可能發生的情況。
最後,我們得到兩個電洞的單重態(singlet state)能量低於鐵磁態,而這就表示兩個電洞的鐵磁態能量並不是最低,也就是說兩個電洞的鐵磁態並不穩定。

Abstract
After the fact that the ferromagnetic state with one hole in a narrow band is ground state has been verified, next comes the question whether the ferromagnetic state with two holes is still the ground state. Researchers have presented diverse ways of taking approximations and doing calculation, but there is no rigorous proof for two holes, and the stability of the ferromagnetic state is still an unsolved problem.
In this thesis, we use Hubbard model, which is presented in 1963 and tight binding method for energy bands to study the problem. The model is determined by a nearest-neighbor transfer matrix t and on-site repulsion U. We take further limit U= to simplify the consideration.
In conclusion, for two holes, we are able to obtain a singlet state with lower energy than that of ferromagnetic state. The ferromagnetic state is no longer the ground state as soon as two holes are present.

目錄
論文摘要(中文)………………………………………………I
論文摘要(英文)………………………………………………II
誌謝………………………………………………………….III
目錄………………………………………………………….IV
第一章簡介………………………………………………1
第二章理論………………………………………………5
第三章能量計算…………………………………………12
  3.1 單一電洞…………………………………………16
  3.2 兩個電洞…………………………………………19
3.2.1 鐵磁態………………………………………22
3.2.2 單重態………………………………………25
第四章結果………………………………………………28
第五章結論………………………………………………30
附錄I…………………………………………………………36
附錄II……………………………………………………….39
附錄III………………………………………………………41
參考文獻……………………………………………………44
簡歷…………………………………………………………47

參考文獻1. Electron correlations in narrow energy bands by J. Hubbard, Proc. Roy. Soc. A276, 238 (1963). 2. On the instability of the ferromagnetic state in the limit of the Hubbard modelby B.Doucot and R. Rammal, Int. J. Mod. Phys. B3, 12(1989). 3. Electron correlation and ferromagnetism of transition metals by J. Kanamori, Prog. Theor. Phys. 30, 275(1963). 4. Ferromagnetism in a narrow, almost half-filled s band by Y. Nagaoka, Phys. Rev. 147, 392(1966).5. Instability of the Nagaoka state with more than one hole by B. Douct and X. G. Wen, Phys. Rev. B40, 4(1989).6. Ground state energy of Hubbard model by W. D. Langer and D. C. Mattis, Phys. Lett. A36, 139(1971).7. Stability of the Nagaoka state in the one-band Hubbard model by Guang-Shan Tian, Phys. Rev. B44, 9(1991). 8. Stability of the saturated ferromagnetic state in the one-band Hubbard model by A.Barbieri, J. A. Riera and A. P. Young, Phys. Rev. B41, 16(1990). 9. Hole-hole correlations in the limit of the Hubbard model and the stability of the Nagaoka state by M. W. Long and X. Zotos, Phys. Rev. B48, 1(1993). 10. Ground state of Hubbard model. Exact solution for two holes by E. V. Kuz’min, JETP Lett. 57, 9(1993). 11. Ferromagnetism in the one-band Hubbard model by J. A. Riera and A. P. Young, Phys. Rev. B40, 7(1989).12. Instability of the Nagaoka ferromagnetic state of the Hubbard model by B. S. Shastry, H. R. Krishnamurthy, and P. W. Anderson, Phys. Rev. B41, 2375(1990).13. Instability of the Nagaoka state with more than one hole B. Doucot and X. G. Wen, Phys. Rev. B40, 4(1989). 14. On the ground state of Hubbard model with strong repulsion by Ju. V. Mikhailova, Int. J. Mod. Phys. B12, 29(1998).15. Nagaoka Ferromagnetism in the two-dimensional infinite Hubbard model by F. Becca and S. Sorella, Phys. Rev. Lett, 86, 15(2001). 16. Gerald D. Mahan, Many-Particle Physics, New York, PlenumPress(1990).17. C. Kittel, Introduction to Solid State Physics, John Wileyand Sons, Inc., New York(1996).

電子全文 電子全文(本篇電子全文限研究生所屬學校校內系統及IP範圍內開放)
QRCODE
 
 
 
 
 
                                                                                                                                                                                                                                                                                                                                                                                                               
第一頁 上一頁 下一頁 最後一頁 top