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Enhancement of d-wave pairing in the extended 2D t-J model

Enhancement of d-wave pairing in the extended 2D t-J model. Y. C. Chen Tunghai University, Taiwan. C. T. Shih , Tunghai University, Taiwan T. K. Lee , Inst. of Physics, Academia Sinica, Taiwan R. Eder , Forschungszentrum, Karlsruhe, Germany

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Enhancement of d-wave pairing in the extended 2D t-J model

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  1. Enhancement of d-wave pairing in the extended 2D t-J model Y. C. Chen Tunghai University, Taiwan C. T. Shih, Tunghai University, Taiwan T. K. Lee, Inst. of Physics, Academia Sinica, Taiwan R. Eder, Forschungszentrum, Karlsruhe, Germany C. Y. Mou, National Tsinghua University, Taiwan cond-mat/0401307

  2. 1913 Onnes • 1972 BCS • 1973 Josephson • 1987 Bednortz and Muller • 1991 P. G. de Gennes • 2003 Abrikosov, Ginzburg and Leggett 歷史上與超導體有關的諾貝爾獎

  3. 1911 Onnes 發現汞在4K的溫度下失去電阻

  4. 1933年荷蘭的邁斯納(Meissner)和奧森菲爾德(Ochsenfeld)共同發現了超導體的一個極為重要的性質。(簡稱Meissner effect) 將超導體放入磁場中，會將其內部的磁場完全排除，其內部磁通量（magnetic flux)保持為零。因此，若將一超導體放在一個普通的磁體上方，則會因排斥作用而懸浮在空中。

  5. 超導體有三個臨界值， • Tc: 臨界溫度 • Hc: 臨界溫度 • Jc: 臨界電流密度 • 這三個值越大時，其應用範圍越廣，不同材料有不同的值，以前低溫超導體，雖然Jc已能達到高度應用價值，但因Tc遠低於液態氮的溫度，為著要先把溫度降低，往往需要花費很大的成本，所以，它們的應用，一直難以推廣.

  6. 第二類超導體

  7. Cooper Pair 電荷 charge 自旋 spin ½ 角動量與磁矩 費米子 (Fermion) 包利不相容原則 (Pauli Exclusion principle) Fermi Surface 動量 k 與 -k 電子與晶格振動相互作用 成為電子對之間的媒介 兩個費米子配對而成等效的玻色子, 合作型的玻色子可在費米面上凝聚形成超導

  8. 比熱　　　 相變

  9. 實驗上關於Cooper Pair的證據 磁通量量子化(magnetic flux ) 穿隧效應(tunneling effect)

  10. 地球科學 地殼的厚度 磁極強度的變化 預測地震 礦產 奈米科技 Scanning SQUID Microscopy 生物磁學 遷徙 演化 生命科學與醫學 國防--偵測潛水艇

  11. 400.8 km/h in 1987

  12. On December 2, 2003, this three-car train set attained a maximum speed of 581 km/h in a manned vehicle run. Yamanashi Maglev Test Line MLX01

  13. 超導發電機 Electric generators made with superconducting wire are far more efficient than conventional generators wound with copper wire. In fact, their efficiency is above 99% and their size about half that of conventional generators. These facts make them very lucrative ventures for power utilities.

  14. Hypres Superconducting Microchip, incorporating 6000 Josephson Junctions.

  15. 超導馬達

  16. 5000 horsepower motor

  17. 這艘船是世界最早的超導體電磁推進船。她在1985年由日本造船振興財團及執日本造船牛耳的三菱重工神戶造船所共同設計製造，為多年研究之成果。全長26公尺，寬10公尺，重250噸。這艘流線型船之造價為50億日圓。這艘船的兩邊各有一個推進器，能產生強大的磁場，電流則以直角對著磁場發送電磁力，從船尾排出海水，藉以推進船身。此船推進器很強，不振動且不製造噪音。這艘船是世界最早的超導體電磁推進船。她在1985年由日本造船振興財團及執日本造船牛耳的三菱重工神戶造船所共同設計製造，為多年研究之成果。全長26公尺，寬10公尺，重250噸。這艘流線型船之造價為50億日圓。這艘船的兩邊各有一個推進器，能產生強大的磁場，電流則以直角對著磁場發送電磁力，從船尾排出海水，藉以推進船身。此船推進器很強，不振動且不製造噪音。

  18. The most ignominious military use of superconductors may come with the deployment of "E-bombs". These are devices that make use of strong, superconductor-derived magnetic fields to create a fast, high-intensity electro-magnetic pulse (EMP) to disable an enemy's electronic equipment. Such a device saw its first use in wartime in March 2003 when US Forces attacked an Iraqi broadcast facility.

  19. High-Temperature Superconducting Cuprates

  20. t=0.43 eV U=5.4=12t t’=-0.07~ -0.2t Hubbard model J=0.128 ~0.3t t-J model constraint Heisenberg model Frustrated Heisenberg model

  21. Projected BCS D-wave S-wave

  22. Quantum Critical Phenomenon

  23. Comments on RVB theory from Varma

  24. Green: Loram Blue: ARPES Red: STM

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