Conclusion and Outlook
Well! it’s so excited to touch the wonderful topics Spintronics, Spin Relaxation and Spin Transport which try to reveal the mechanism and details of the interaction between spin and micron (or submicron) structure. There are still many topics and details worth and waitting for researching advancedly related to the contents of this thesis, but here we just indicate three representative key points to be as the conclusion and outlook of this thesis.
The …rst point is the e¤ectiveness and advantage of the usage of the semi-classical approach. It is above suspicion about the advantage of the application of semiclassical approach, the semiclassical approach o¤ers an intuitive viewpoint and convenient handling about the behavior of submicron structure action, but I think that the behavior of the action of submicron structure (e.g. spin relaxation of electrons in real material, etc.) is so subtle and complicated, the questions of the e¤ectiveness of such semiclassical treatment are raised. The connection and/or cor-relation between classical mechanics viewpoint and quantum mechanics viewpoint still waitting for exploring more advancedly.
The second point is the plenty aspects about the topics spin relaxation and spin transport and so on. As the contents of this thesis we found that there are so many
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factors which could a¤ect the spin evolution of the traveling electrons. Well! such aspects o¤er a so wonderful and plenty regiom to explore them more detailedly and completely. I think there are many magic and unexpected unknowns will be appeared as we touch such topics more advancedly. Basically speaking the reason is due to the spin is so novel to our intuition and realization. So it is well above suspicion the complexity of interaction between spin and environment. Finally let us turn our focus from academic viewpoint to the point of view of application to end up the thesis.
The last point about the conclusion and outlook of this thesis is the information about the control the spin o¤ered from the thesis. Spintronics is so fascinating and with great application potential in next generation electronic industry, whether or not the success in application of spintronics maybe determine whether the improve-ment of the civilness of mankind in future. I feel a little suspicious and cheerful about the application potential in terms of the approach of spin control from the research of the thesis. Let us give an example to illustrate the viewpoint of sus-picion, in fact the simulation in our thesis is totally lay under the ideal situation, and even in such ideal situation the wavevectors (velocities) of electrons exhibit an adequately broad distribution aspect, reference Fig. 7.1, so we could expect the spin relaxation rate is more fast when we proceed the operation (simulation) under the action of combination of many operation cases, see Fig. 7.8 et al. If this aspect is true, well! unfortunately the possibility of the application of spintronics, especially for in terms of the spin control approach is lowered. About the part of
cheer, the reason comes from that we …nd the enough long about the relaxation time which exhibited from our thesis. From the point of view of the improvement of modern industrial techniques, such long relaxation time owns the so great po-tential in practical application. Anyhow there are existing many problems which obstruct the advancement of the practical application in the point of view of spin control, e.g. the injection of nonequilibrium electronic spin is still a big problem nowadays and so on. However the experimental exploration and demonstration and the theoretically fundamental research are still necessary hurry-scurry in future!
In one word nature is so novel and unexpected inspired by the nature exploration history, at present we even could not realize what happened about and even predict the position of an electron in next moment, who know what happened about the nature in future!?
References
[1] S. Datta, Electronic Transport in Mesoscopic Systems (Cambridge University Press, Cambridge, 1995).
[2] S. Das Sarma et al., Phys. Rev. B 32, 8442 (1988).
[3] M. L. Roukes et al., Phys. Rev. Lett. 59, 3011 (1987).
[4] C. J. B. Ford et al., Phys. C 21, L325 (1988).
[5] C. J. B. Ford et al., Phys. Rev. Lett. 62, 2724 (1989).
[6] C. M. Marcus et al., Phys. Rev. Lett. 69, 506 (1992).
[7] M. J. Berry et al., Phys. Rev. B 50, 8857 (1994).
[8] A. M. Chang et al., Phys. Rev. Lett. 73, 2111 (1994).
[9] R. M. Clarke et al., Phys. Rev. B 52, 2656 (1995).
[10] R. P. Taylor et al., Phys. Rev. Lett. 78, 1952 (1997).
[11] A. G. Huibers et al., Phys. Rev. Lett. 81, 1917 (1998).
[12] A. S. Sachrajde et al., Phys. Rev. Lett. 80, 1948 (1998).
[13] M. C. Gutzwiller, Chaos in Classical and Quantum Mechanics (Springer-Verlag, Berlin, 1990).
[14] S. Datta et al., Appl. Phys. Lett. 56(7), 665 (1990).
[15] S. J. Pearton et al., J. Appl. Phys. 93, 1 (2003).
154
[16] H. Ohno, Science 281, 951 (1998).
[17] V. Dediu et al., Solid State Commu. 122, 181 (2002).
[18] D. A. Pejakovi´c et al., Phys. Rev. Lett. 88, 057202 (2002).
[19] K. Tsukagoshi et al., Nature (London) 401, 572 (1999).
[20] B. Zhao et al., Appl. Phys. Lett. 80, 3144 (2002).
[21] I. Zutic et al., Rev. Mod. Phys. 76, 323 (2004).
[22] F. Bloch, Phys. Rev. 70, 460 (1946).
[23] H. C. Torrey, Phys. Rev. 104, 563 (1956).
[24] J. I. Kaplan, Phys. Rev. 115, 575 (1959).
[25] D. Loss et al., Phys. Rev. A 57, 120 (1998).
[26] M. A. Brand et al., Phys. Rev. Lett. 89, 236601 (2002).
[27] S. Namba, J. Phys. Soc. Jpn. 63, 224 (1994).
[28] J. Nitta et al., Phys. Rev. Lett. 78(7), 1335 (1997).
[29] J. M. Elzerman et al., Nature 430, 431 (2004).
[30] D. J. Gri¢ ths, Introduction to Quantum Mechanics (Prentice Hall, Inc. 1995).
[31] H. C. Ohanian, Am. J. Phys. 54, 500 (1986).
[32] D. Hestenes, Am. J. Phys. 47(5) (1979).
[33] D. Gri¢ ths, Introduction to Electrodynamics, 3rd ed. (Prentice-Hall Interna-tional, Inc. 1999).
[34] H. Goldstein, Classical Mechanics (Addison-Wesley Publishing Company, 1980).
[35] J. J. Sakurai, Modern Quantum Mechanics, revised ed. (Addison-Wesley Pub-lishing Company, Inc. 1994).
156
[36] J. J. Sakurai, Advanced Quantum Mechanics (Addison-Wesley, Reading, MA, 1967).
[37] R. J. Elliot: See E. N. Adamas, II, Phys. Rev. 92, 1063 (1953), reference 7.
[38] G. Dresselhause et al., Phys. Rev. 95, 568 (1954).
[39] R. H. Parmenter, Phys. Rev. 100(2), 573 (1995).
[40] G. Dresselhause, Phys. Rev. 100(2), 580 (1995).
[41] S. V. Kravchenko et al., Phys. Rev. B. 50(11), 8039 (1994).
[42] V. M. Pudalov, JETP Lett. 66, 175 (1997).
[43] S. J. Papadakis et al., Science 283, 2056 (1999).
[44] H. Ohno (Ed.), vol. 10 of Physica E (2001).
[45] C. Kittel, Quantum Theory of Solids (Wiley, New York, 1963).
[46] Y. A. Bychkov et al., J. Phys. C: Solid State Phys. 17, 6039 (1984).
[47] U. Rössler et al., Solid State Commun. 121, 313 (2002).
[48] G. Goldoni et al., Phys. Rev. Lett. 69(17), 2567 (1992).
[49] R. Winkler, Spin-Orbit Coupling E¤ects in Two-Dimensional Electron and Hole Systems (Springer, 2003).
[50] The main idea to make such connection is due to Hui-Fen Lo et al. from private communication (2006).
[51] M. Cardona et al., Phys. Rev. B. 38(3), 1806 (1988).
[52] D. G. Seiler et al., Phys. Rev. B. 16(6), 2822 (1977).
[53] H. Riechert et al., Phys. Rev. Lett. 52(25), 2297 (1984).
[54] R. Eppenga et al., Phys. Rev. B. 37, 10923 (1988).
[55] R. Winkler, Phys. Rev. B. 69, 045317 (2004).
[56] C. Jung et al., J. Phys. A. 21, 2301 (1988).
[57] H. U. Baranger et al., Chaos. 3, 665 (1993).
[58] P. Gaspard et al., J. Chem. Phys. 90, 2225; 2242; 2255 (1989).
[59] R. V. Jensen, Chaos. 1, 101 (1991).
[60] N. W. Ashcroft et al., Solid State Physics (Holt Rhinehart, and Winston, New York, 1976).
[61] H. U. Baranger et al., Phys. Rev. B. 54, R14297 (1996).
[62] D. C. Langreth et al., Phys. Rev. B. 24, 2978 (1981).
[63] H. U. Baranger et al., Phys. Rev. B. 40, 8169 (1989).
[64] D. S. Fisher et al., Phys. Rev. B. 23, 6851 (1981).
[65] M. Buttiker, Phys. Rev. Lett. 57, 1761 (1986).
[66] R. A. Jalabert et al., Phys. Rev. Lett. 65, 2442 (1990).
[67] A. G. Mal’shukov et al., Phys. Rev. B 66, 081311(R) (2002).
[68] R. Fiederling et al., Nature (London) 402, 787 (1999).
[69] A. T. Hanbicki et al., con-mat/0110059.
[70] J. C. Egues, Phys. Rev. Lett. 80, 4578 (1998).
[71] R. Blümel et al., Phys. Rev. Lett. 60, 477 (1988).
[72] Cheng-Hung Chang et al., Phys. Rev. B 70, 245309 (2004).
[73] The prototype of simulation programs for spin relaxation topic is mainly come from Cheng-Hung Chang, and that for spin transport topic is partially come from Cheng-Hung Chang (2006).
[74] Cheng-Hung Chang et al., Physics Letter A 326, 436-441 (2004).
Vita
Jengjan Tsai, a boy was born in 1968 in Tainan city of the Republic of China (R.O.C.). His learning process is B.S. (Mechanical Engineering) in National Tai-wan University of Science and Technology (1999), M.S. (Physics) in National Chiao Tung University (2006) et al. He is a boy who likes and loves the natural world.
He likes the life with a simple way since he is not a wheeler-dealer. At present there are still many tasks waitting for running after for him. He strongly desires to execute him dream in his life, a nice job (which o¤er just enough income for living), a nice residence, a lovely girl, enjoy the world, enjoy math and physics, help others (families, people, living objects, environment, the world et al.) and so on.
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