(3.238.174.50) 您好!臺灣時間:2021/04/18 17:45
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:沈育佃
研究生(外文):Shen, Yu-Tien
論文名稱:鐵硒碲與金的C軸方向穿隧元件中電導能譜與超導能隙結構之研究
論文名稱(外文):Conductance spectra and superconducting gap structures observed in c-axis FeSe0.3Te0.7 / Au junctions
指導教授:齊正中
指導教授(外文):Chi, Cheng-Chung
學位類別:博士
校院名稱:國立清華大學
系所名稱:物理系
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:2013
畢業學年度:101
語文別:英文
論文頁數:83
中文關鍵詞:鐵基超導超導-金屬元件電導能譜超導能隙
外文關鍵詞:iron based superconductorsc-axis superconductor-normal junctiontunneling spectragap structures
相關次數:
  • 被引用被引用:0
  • 點閱點閱:105
  • 評分評分:系統版面圖檔系統版面圖檔系統版面圖檔系統版面圖檔系統版面圖檔
  • 下載下載:4
  • 收藏至我的研究室書目清單書目收藏:0
我們將雷射濺鍍法成長出來的鐵硒碲薄膜製作成C方向的鐵硒碲-金穿遂元件,並研究分析該元件的電導能譜。實驗中,當量測的溫度低於鐵硒碲的超導溫度時,除了明顯的ZBCP現象產生外其它的類似超導能隙的結構也隨著鐵硒碲的超導特性而產生。由於這些結構隨著磁性以及溫度的變化,有著相應的反應,該結構可以被認定為與超導特性有關連。透過extended BTK理論的計算,我們的實驗結果可以被模擬出來,鐵硒碲的兩個超導能隙大小在兩個樣品中分別為4、6meV以及7、10.5meV。雖然兩個樣品上看到的數值有差異,不過兩個超導能隙的比例均為1.5。在更高偏壓的區域,我們還發現了另一個大結構的類超導能隙結構。除此之外,我們還發現了通氧可讓鐵硒碲薄膜的超導特性變好的結果。
The electric transport properties of superconducting c-axis FeSe0.3Te0.7/Au (S/N) junctions, fabricated using pulsed laser deposition, have been investigated in the temperature range of 2 K to the superconducting transition temperature Tc, and in the presence of applied magnetic fields from 0 to 9 T. A large zero-bias conductance peak has always been observed in every conductance spectrum of the junctions. In addition, we have found several gap-like features. Using the extended BTK theory with the currently favored nodeless s±-wave symmetry, our conductance spectrum can be reproduced qualitatively with Δ1 = 4 meV, and Δ2 = 6 meV at 2 K in sample #1 and Δ1 = 7 meV, and Δ2 = 10.5 meV at 2 K in sample #2. Although there is an inconsistency of the gap values in FeSeTe, the relative ratio between two gaps are both 1.5, which is the same as the published ARPES data for FeSeTe samples of similar compositions. We note that the experimental conductance spectra are substantially below the one calculated in the high bias range. Furthermore, there are unaccounted conductance minima at approximately 15.4 meV (20 meV) in junction #1 (#2) whatever the cause for these conductance minima may also be the reason for the discrepancy. In addition, we have accidentally encountered an interesting Tc enhancement effect due to oxygen-annealing effect for the pulse-deposited FeSeTe thin films. The Tc of the as-grown thin film can be increased up to 3 K after an oxygen-annealing process.
Abstract i
Acknowledgement ii
Table of Contents iv
List of Figures vi
List of Tables xi

Chapter 1: Introduction 1
1-1. History of Superconductors 1
1-2. Introduction to Iron-Based Superconductors 3
1-3. Motivation of This Thesis 6

Chapter 2: Theory 7
2-1. Conventional BTK Theory 7
2-1.1. Andreev Reflection 8
2-1.2. Derivation of the BTK Theory 8
2-2. Generalized BTK Theory with d-Wave Superconductor 16
2-3. Generalized BTK Theory with s±-Wave Superconductor 20

Chapter 3: Thin Film and Junction Fabrication 23
3-1. Introduction to Thin Film Fabrication System 23
3-1.1. Pulse Laser Deposition System 24
3-1.2. Thermal Evaporation System 27
3-2. Quality of the FeSeTe Thin Films 29
3-2.1. Transport Properties 29
3-2.2. X-ray Diffraction Patterns 33
3-2.3. Rutherford Backscattering Spectrometry 35
3-2.4. Other Measurements 37
3-3. Fabrication of the c-axis FeSeTe / Au Junctions 39
3-3.1. Introduction to Photolithography Process 40
3-3.2. Fabrication Process of the S/N Junctions 43

Chapter 4: c-axis FeSeTe / Au Junction Measurement 46
4-1. Experimental Setup of the Differential Conductance
Measurement System 46
4-2. Measurements of R-T Behavior of the Junctions 47
4-3. Differential Conductance Spectra of the Junctions 50
4-3.1.Temperature Dependence of Conductance Spectra 50
4-3.2. Magnetic Field Dependence of Conductance Spectra 57

Chapter 5: Simulation Results and Discussion 67
5-1. Zero Bias Conductance Peak 67
5-2. Simulation Based on Nodeless s±-wave Symmetry 69
5-3. Discussion 72

Chapter 6: Conclusion 77

Appendix: Fourier Analysis 78
References 80

[1] H. Kamerlingh Onnes, Leiden Comm. 120b, 122b, 122c (1911)
[2] J. R. Gavaler, Appl. Phys. Lett. 23 (1973) 480
[3] J. G. Bednorz and K. A. Muller, Z. Phys. B. 64 (1986) 198
[4] M. K. Wu, J. R. Ashburn, and C. J. Torng, Phys. Rev. Lett. 58 (1987) 908
[5] Hiroshi Maeda, Yoshiaki Tanaka, Masao Fukutomi, and Toshihisa Asano, Jpn, J. Appl. Phys. 27 (1988) L209
[6] Z. Z. Sheng and A. M. Hermann, Nature 332 (1988) 55
[7] C. W. Chu, L. Gao, F. Chen, Z. J. Huang, R. L. Meng, and Y. Y. Xue, Nature 365 (1993) 323
[8] H. Bardeen, L. N. Cooper, and J. R. Schrieffer, Phys. Rev. 108 (1957) 1175
[9] C. C. Tsuei, J. R. Kirtley, M. Rupp, J. Z. Sun, A. Gupta, M. B. Ketchen, C. A. Wang, Z. F. Ren, J. G. Wang, and M. Bhushan, Science 271 (1996) 329
[10] C. C. Tsuei and J. R. Kirtley, Rev. Mod. Phys. 72 (2000) 969
[11] C. C. Tsuei, J. R. Kirtley, G. Hammerl, J. Mannhart, H. Raffy, and Z. Z. Li, Phys. Rev. Lett. 93 (2004) 187004
[12] H. J. H. Smide, A. A. Golubov, Ariando, G. Rijnders, J. M. Dekkers, S. Harkema, D. H. A. Blank, H. Rogalla, and H. Hilgenkamp, Phys. Rev. Lett. 95 (2005) 257001
[13] Y. Kamihara, H. Hiramatsu, M. Hirano, R. Kawamura, H. Yanagi, T. Kamiya, and H. Hosono, J. Am. Chem. Soc. 128 (2006) 10012
[14] Y. Kamihara, T. Watanabe, M. Hirano, and H. Hosono, J. Am. Chem. Soc. 130 (2008) 3296
[15] M. Rotter, M. Tegel, and D. Johrendt, Phys. Rev. Lett. 101 (2008) 107006
[16] X. C. Wang, Q. Q. Liu, Y. X. Lv, W. B. Gao, L. X. Yang, R. C. Yu, F. Y. Li, and
C. Q. Jin, Solid State Commun. 148 (2008) 538
[17] F. C. Hsu, J. Y. Luo, K. W. Yeh, T. K. Chen, T. W. Huang, P. M. Wu, Y. C. Lee, Y. L. Huang, Y. Y. Chu, D. C. Yan, M. K. Wu, Proc. Natl. Acad. Soc. U. S. A. 105 (2008) 14262
[18] H. Ogino, Y. Matsumura, Y. Katsura, K. Ushiyama, S. Horii, K. Kishio, and J. Shimoyama, Supercond. Sci. Technol. 22 (2009) 075008
[19] Wei Bao, G. N. Li, Q. Huang, G. F. Chen, J. B. He, M. A. Green, Y. Qiu, D. M. Wang, J. L. Luo, arxiv: 1102.3674
[20] Y. Mizuguchi. F. Tomioka, S. Tsuda, T. Yamaguchi, and Y. Takano, Appl. Phys. Lett. 93 (2008) 152505
[21] S. Medvedev, T. M. McQueen, I. A. Troyan, T. Palasyuk, M. I. Eremets, R. J. Cava, S. Naghavi, F. Casper, V. Ksenofontov, G. Wortmann, and C. Felser, Nature Matter. 8 (2009) 630
[22] S. Masaki, H. Kotegawa, Y. Hara, H. Tou, K. Murata, Y. Mizuguchi, and Y. Takano, J. Phys. Soc. Jpn. 78 (2009) 063704
[23] T. Imai, K. Ahilan, F. L. Ning, T. M. McQueen, R. J. Cava, Phys. Rev. Lett. 102 (2009) 177005
[24] K. W. Yeh, T. W. Huang, Y. L. Huang, T. K. Chen, F. C. Hsu, P. M. Wu, Y. C. Lee, Y. Y. Chu, C. L. Chen, J. Y. Luo, D. C. Yan, and M. K. Wu, EPL 84 (2008) 37002
[25] M. H. Fang, H. M. Pham, B. Qian, T. J. Liu, E. K. Vehstedt, Y. Liu, L. Spinu, and Z. Q. Mao, Phys. Rev. B, 78 (2008) 224503
[26] P. A. Lee and X. G. Wen, Phys. Rev. B, 78 (2008) 144517
[27] Q. Si and E. Abrahams, Phys. Rev. Lett. 101 (2008) 076401
[28] F. Wang, H. Zhai, Y. Ran, A. Vishwanath, and D. H. Lee, Phys. Rev. Lett. 102 (2009) 047005
[29] A. V. Chubukov, D. V. Efremov, and I. Eremin, Phys. Rev. B, 78 (2008) 134512
[30] K. Seo, B. A. Bernevig, and J. Hu, Phys. Rev. Lett. 101 (2008) 206404
[31] W. Q. Chen, K. Y. Yang, Y. Zhou, and F. C. Zhang, Phys. Rev. Lett. 102 (2009) 047006
[32] I. I. Mazin, D. J. Singh, M. D. Johannes, and M. H. Du, Phys. Rev. Lett. 101 (2008) 057003
[33] C. T. Chen, C. C. Tsuei, M. B. Ketchen, Z. A. Ren, Z. X. Zhao, Nat. Phys. 6 (2010) 260
[34] T. Hanaguri, S. Niitaka, K. Kuroki, H. Takagi, Science 328 (2010) 474
[35] C. L. Song, Y. L. Wang, P. Cheng, Y. P. Jiang, W. Li, T. Zhang, Z. Li, K. He, L. Wang, J. F. Jia, H .H. Hung, C. Wu, X. Ma, X. Chen, Q. K. Xue, Science, 332 (2011) 1410
[36] G. E. Blonder, M. Tinkham, and T. M. Klapwijk, Phys. Rev. B, 25 (1982) 4515
[37] Yukio Tanaka and Satoshi Kashiwaya, Phys. Rev. Lett. 74 (1995) 3451
[38] A. A. Golubov, A. Brinkman, Yukio Tanaka, I. I. Mazin, and O. V. Dolgov, Phys. Rev. Lett. 103 (2009) 077003
[39] Hefei Hu, Jian-Min Zuo, Mao Zheng, James N. Eckstein, Wan Kyu Park, Laura H. Greene, Jinsheng Wen, Zhijun Xu, Zhiwei Lin, Qiang Li, and Genda Gu, Phys. Rev. B 85 (2012) 06450
[40] M.K. Wu, F.C. Hsu, K.W. Yeh, T.W. Huang, J.Y. Luo, M.J. Wang, H.H. Chang, T.K. Chen, S.M. Rao, B.H. Mok, C.L. Chen, Y.L. Huang, C.T. Ke, P.M. Wu, A.M. Chang, C.T. Wu, T.P. Perng, Phys. C 469 (2009) 340
[41] J. A. Appelbaum, Phys. Rev. 154 (1967) 633
[42] H. Miao, P. Richard, Y. Tanaka, K. Nakayama, T. Qian, K. Umezawa, T. Sato, Y.-M. Xu, Y. B. Shi, N. Xu, X.-P. Wang, P. Zhang, H.-B. Yang, Z.-J. Xu, J. S. Wen, G.-D. Gu, X. Dai, J.-P. Hu, T. Takahashi, and H. Ding, Phys. Rev. B, 85 (2012) 094506
[43] Y. S. Li, C. C. Chi, unpublished
[44] Q. Y. Wang, Z. Li, W. H. Zhang, Z. C. Zhang, J. S. Zhang, W. Li, H. Ding, Y. B. Ou, P. Deng, K, Chang, J. Wen, C. L. Song, K. He, J. F. Jia, S. H. Ji, Y. Y. Wang, L. L. Wang, X Chen, X. C. Ma, and Q. K. Xue, Chin. Phys. Lett. 29 (2012) 037402
[45] K. C. Lin, Y. S. Li, Y. T. Shen, M. K. Wu and C. C. Chi, arXiv:1305.3749, 2013
[46] Y.-B. Huang, P. Richard, X.-P. Wang, T. Qian and H. Ding, AIP ADVANCES 2, 041409 (2012)
連結至畢業學校之論文網頁點我開啟連結
註: 此連結為研究生畢業學校所提供,不一定有電子全文可供下載,若連結有誤,請點選上方之〝勘誤回報〞功能,我們會盡快修正,謝謝!
QRCODE
 
 
 
 
 
                                                                                                                                                                                                                                                                                                                                                                                                               
第一頁 上一頁 下一頁 最後一頁 top
系統版面圖檔 系統版面圖檔