跳到主要內容

臺灣博碩士論文加值系統

(44.210.85.190) 您好!臺灣時間:2022/12/06 01:14
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

: 
twitterline
研究生:林承風
研究生(外文):Cheng-Feng Lin
論文名稱(外文):Spin transport calculation for thiol-ended single-molecule magnetic junction
指導教授:唐毓慧
指導教授(外文):Yu-Hui Tang
學位類別:碩士
校院名稱:國立中央大學
系所名稱:物理學系
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:2016
畢業學年度:104
語文別:英文
論文頁數:70
中文關鍵詞:單分子通道磁阻自旋傳輸第一原理計算
外文關鍵詞:single molecular junctionsmagnetoresistancespin transportfirst-principles calculation
相關次數:
  • 被引用被引用:0
  • 點閱點閱:117
  • 評分評分:
  • 下載下載:5
  • 收藏至我的研究室書目清單書目收藏:0
我們利用第一原理計算方法,先由以密度泛函理論為基礎的Quantum ESPRESSO 程序優化單一分子隧結 Ni/1,4-alkanedithiol(ADT)/Ni的結構,然後增加右邊Ni adatom與電極間的距離,進行結構優化,再重複以上步驟來模擬實驗上拉伸的過程,直到找到此單一分子隧結模型的斷裂點。我們接者再由應用了非平衡格林函數結合密度泛函理論與廣義梯度近似方法來計算在斷裂點時的projected density of states與transmission spectrum. 與應力相關的自旋極化穿隧頻譜可以透過Ni adatom的拓寬的自旋向上PDOS結合高低不平的自旋向下PDOS來了解。因為中間的以σ鍵為主的ADT分子是導電性較差的,以及由透過Ni adatom的直接穿隧主導穿隧機率。我們進一步計算了在斷裂點的電流-電壓特性以及磁阻率。令人驚訝的,在拉伸下對於導電性較差的以σ鍵為主的ADT單一分子接面的磁阻率值可達到至200%。
We employed the density-functional theory (DFT) within the generalized approximations (GGA) in the PBE form, to simulate the Ni/1,4-alkanedithiol(ADT)/Ni single-molecule magnetic junction under stretching process. The junction is stretched by increasing the distance between two Ni nanowires in small steps, optimize it again, and continue to do so, until the junction breaks down. The First-principle spin transport calculation is based on the non-equilibrium Green’s functions formalism and the DFT approach. The strain dependence of spin-polarized transmission spectra can be understood by the broad spin-up PDOS combined with the spiky spin-down PDOS of Ni adatom. This is because the central σ-saturated ADT molecule is less conductive and the transmission probability is dominated by the direct tunneling via the Ni adatom. We further calculated the I-V characteristic of breaking point and get the magnetoresisitance (MR). Surprisingly, the giant value about 200% and the bias-induced of MR can be found in this less conductive σ-saturated Ni/1,4-alkanedithiol(ADT)/Ni single molecular junction under the stretching.
Chapter 1 Introduction 1
Chapter 2 Theory 7
2.1 Density Function Theory 7
2.1.1 Born-Oppenheimer Approximation 8
2.1.2 The Hohenberg-Kohn Theorem 9
2.1.3 The Kohn-Sham Equation 11
2.1.4 Exchange-Correlation Energy Functionals 16
Local Density Approximation (LDA) 16
Generalized Gradient Approximation (GGA)18
2.1.5 Pseudopotential Method 19
2.1.6 Basis Functions 21
2.2 Non-Equilibrium Green’s Function Method 21
2.2.1 The NEGF formalism 22
Chapter 3 Computational Details 29
3.1 Structural Geometry 29
3.2 Parameters for Structural Relaxation Calculation 30
3.3 Parameters for Spin Transport Calculation 32
Chapter 4 Results and Discussion 34
4.1 Structural Relaxation during Stretching 37
4.2 Spin-Transport Properties 37
4.3 Spin-Polarized Current and Magnetoresistance 43
Chapter 5 Summary 52
References 53
[1] M. N. Baibich, J. M. Broto, A. Fert, F. N. Van Dau, F. Petroff, P. Etienne, G. Creuzet, A. Friederich, and J. Chazelas, Physical Review Letters 61, 2472 (1988).
[2] G. Binasch, P. Grünberg, F. Saurenbach, and W. Zinn, Physical Review B 39, 4828 (1989).
[3] B. Dieny, V. S. Speriosu, S. S. P. Parkin, B. A. Gurney, D. R. Wilhoit, and D. Mauri, Physical Review B 43, 1297 (1991).
[4] C. Chappert, A. Fert, and F. N. Van Dau, Nat Mater 6, 813 (2007).
[5] M. Julliere, Physics Letters A 54, 225 (1975).
[6] S. Maekawa and U. Gafvert, Magnetics, IEEE Transactions on 18, 707 (1982).
[7] T. Miyazaki and N. Tezuka, Journal of Magnetism and Magnetic Materials 139, L231 (1995).
[8] J. S. Moodera, L. R. Kinder, T. M. Wong, and R. Meservey, Physical Review Letters 74, 3273 (1995).
[9] S. Yuasa, T. Nagahama, A. Fukushima, Y. Suzuki, and K. Ando, Nat Mater 3, 868 (2004).
[10] S. S. P. Parkin, C. Kaiser, A. Panchula, P. M. Rice, B. Hughes, M. Samant, and S.-H. Yang, Nat Mater 3, 862 (2004).
[11] M. A. Reed, C. Zhou, C. J. Muller, T. P. Burgin, and J.M. Tour. Conductance of molecular junction. Science 278, 252-254 (1997).
[12] M. Di Ventra, S. T. Pantelides, and N. D. Lang. First Principle Calculation of Transport Properties of a Molecule Device. Phys. Rev. Lett. 84,979 (2000)
[13] A.. R. Rocha, V. M. Garcia-Suarez, S. W. Bailey, C. J. Lambert, J. Ferrer, and S. Sanvito. Towards molecular spintronics. Nature Mater. 4, 335-339 (2005)
[14] S. Sanvito, Nat Phys 6, 562 (2010).
[15] D. Waldron, P. Haney, B. Larade, A. MacDonald, and H. Guo, Physical Review Letters 96, 166804 (2006).
[16] Z. Ning, Y. Zhu, J. Wang, and H. Guo, Physical Review Letters 100, 056803 (2008).
[17] B. Q. Xu, X. L. Li, X. Y. Xiao, H. Sakaguchi, and N. J. Tao, Nano Lett 5, 1491 (2005).
[18] Y. H. Tang, N. Kioussis, A. Kalitsov, W. H. Butler, and R. Car, Physical Review B 81, 054437 (2010).
[19] M. Born and R. Oppenheimer, Annalen der Physik 389, 457 (1927).
[20] Thomas L H. Proc. Cambridge Phil. Soc. , 1927 , 23 : 5422548.
[21] Fermi E Z. Phys. , 1928 , 48 : 73-79.
[22] Dirac P A M. Proc. Cambridge Phil. Soc. , 1930 , 26 : 3762385.
[23] P. Hohenberg and W. Kohn, Physical Review 136, B864 (1964).
[24] W. Kohn and L. J. Sham, Physical Review 140, A1133 (1965).
[25] L. Hedin and B. I. Lundqvist, J. Phys. C: Solid State Phys. 4, 2064 (1971).
[26] Ceperley D M , Alder B J . Phys. Rev. Lett . , 1980 , 45 (7) : 566-569.
[27] Perdew J P , Zunger A. Phys. Rev. B , 1981 , 23 (10) : 5048-5079.
[28] U. von Barth and L. Hedin, J. Phys. C: Solid State Phys. 5, 1629 (1972).
[29] Becke A D. Phys. Rev. A , 1988 , 38 ( 6 ) : 3098-3100.
[30] Lee C , Yang W , Parr R G. Phys. Rev. B , 1988 , 37 (2) : 785-789.
[31] Perdew J P. In : Ziesche P , Eschrig H. Editors. Electronic St ructure of Solids. Akademie Verlag , Berlin , 1991. Vol. 11.
[32] Perdew J P , Burke K, Ernzerhof M. Phys. Rev. Lett . 1996 , 77 (18) : 3865-3868.
[33] Hamann D R , Schl ' uter M , Chiang C. Phys. Rev. Lett . 1979 , 43 (20) : 1494-1497.
[34] Bachelet G B , Hamann D R , Schl ' uter M. Phys. Rev. B , 1982 , 26 (8) : 4199-4228.
[35] Vanderbilt D. Phys. Rev. B , 1990 , 41 ( 11 ) : 7892-7895.
[36] W. C. Herring, Phys. Rev. 57, 1169 (1940).
[37] W. C. Herring and A. G. Hill, Phys. Rev. 58: 132, 1940.
[38] Blochl P E. Phys. Rev. B , 1994 , 50 ( 24 ) : 17953-17979.
[39] Datta S. Elect ronic Transport in Mesoscopic System , England : Cambridge University Press , 1997.
[40] Taylor J . Ab-initio Modelling of Transport in Atomic Scale Devices , PhD thesis , Canada : McGill University , 2000.
[41] http://quantumwise.com/
[42] Computational aspects of electronic transport in nanoscale devices , Hans Henrik Brandenborg Sørensen , Kongens Lyngby 2008.
[43] J. Taylor, H. Guo, and J. Wang, Physical Review B 63, 245407 (2001).
[44] Sanvito S , Lambert C J , J efferson J H , et al. Phys.Rev. B , 1999 , 59 (18) : 11936211948 J. Taylor, H. Guo, J. Wang, Phys. Rev. B 63, 245407 (2001).
[45] Sancho M P L , Sancho J M L , Rubio J J . Phys. F : Met . Phys. , 1984 , 14 : 120521215.
[46] M. Brandbyge, J.-L. Mozos, P. Ordejón, J. Taylor, and K. Stokbro, Phys. Rev. B,65, 165401, 2002, 65, 165401.
[47] Quantum ESPRESSO, http://www.quantum-espresso.org/

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
無相關期刊