臺灣博碩士論文加值系統

吾人仿TMR(Tunneling Magnetoresistance)三明治結構，並選擇上下鐵磁層使用龐磁阻(CMR)材料中之La0.67Sr0.33MnO3(113)，而中間層以具備晶格匹配和具反鐵磁(AFM)特性之La0.67Sr0.33MnO3 · SrO(214)代替一般之SrTiO3，即FM-AFM-FM，目的是為了利用此結構加強SPT (Spin Polarization Tunneling)效應及以自旋電子在反鐵磁超晶格結構中周期性自旋翻轉之構想，有效提升龐磁阻材料之低場磁阻(LFMR)效應。
實驗結果顯示，在吾人製備TMR穿遂元件之製程中，可能造成薄膜結構破壞(例如ion etching之過程)，因此須改進process，以得到更精確之結果。另一方面，由於La0.67Sr0.33MnO3的磁矩排列狀況不穩定，日後可以使用較穩定之La0.67Ca0.33MnO3來改善。

We imitated the sandwich structure of TMR(Tunneling Magnetoresistance) to apply to CMR(Colossal Magnetoresistance) material . We choose one of the Colossal Magnetoresistance material La0.67Sr0.33MnO3(113) to be the Ferromagnetic(FM) layers as top and bottom layer in sandwich structure and use La0.67Sr0.33MnO3 · SrO(214) to be middle layer which have Antiferromagnetic(AFM) property to form FM-AFM-FM structure. The FM and AFM layer can match their lattice in interface joint. What its purpose is to use this structure to enhance SPT (Spin Polarization Tunneling) effect and let spintronics can periodical spin-flip in supper lattice structure of antiferromagnetic. Upon this compose we try to show increase the LFMR (Low Field Magnetoresistance) by use CMR.
The experiment result shows maybe the film structure damage occurred in our made TMR tunneling device process (ex. Ion etching process), so we should improvement the process to get the exactly experiment data. Additional, due to the alignment of the moment of La0.67Sr0.33MnO3 is unstable, the back and forth hysteresis loop can’t overlap, So that afterwards we can use the more stable material La0.67Ca0.33MnO3 which have more stable moment.

摘 要
第一章簡介………………………………………………1
第二章基本理論…………………………………………3
2-1 磁性物質…………………………………………………3
2-2 材料之物理特性及超巨磁阻相關理論……………...…11
2-2-1 晶格結構………………………………………..11
2-2-2 磁阻介紹……………………………………….14
2-2-3 雙交換機制模型(Double-Exchange Model)…..19
2-2-4 Jahn-Teller(JT)效應……………………………23
2-3 自旋極化穿隧(spin polarization tunneling)……………25
第三章實驗方法………………………………………...33
3-1 實驗儀器設備之簡介…………………………………..33
3-1-1 薄膜製程之濺鍍系統………………………….33
3-1-2 電性及磁阻量測系統………………………….35
3-2 樣品製備………………………………………………..39
3-2-1 薄膜成長環境…………………………………39
3-2-2 SDT(spin-dependent tunneling)元件結構…….40
3-2-3 電性及磁阻量測………………………………40
第四章實驗結果與討論……………………………….42
4-1 La0.67Sr0.33MnO3 (113)之物理特性……………………42
4-1-1 La0.67Sr0.33MnO3 (113) 塊材(bulk) 物性之量測..42
4-1-2 La0.67Sr0.33MnO3 (113) 薄膜(film) 物性之量測..44
4-2 La0.67Sr1.33MnO4 (214)之物理特性…………………...47
4-2-1 La0.67Sr1.33MnO4 (214) 塊材(bulk) 物性之量測..47
4-3 純La0.67Sr0.33MnO3 (113)穿隧元件量測…………….48
4-4 12min (214)中間層之量測…………………………..52
4-4-1 12min之橫向電流量測……………………..52
4-4-2 12min之縱向電流R-T量測………………..54
4-4-3 12min之縱向電流I-V量測………………...55
4-4-4 12min之縱向電流MR量測………………..57
4-5 3min (214)中間層之量測…………………………….58
4-5-1 3min之橫向電流之R-T量測………………58
4-5-2 3min之縱向電流R-T量測…………………59
4-5-3 3min之縱向電流I-V量測………………….61
4-5-4 3min之縱向電流M-R量測………………...64
第五章結論……………………………………………..69
參考資料…………………………………………………..70

[1] M. N. Baibich, etal, Phys. Rev. Lett, 61, 2472(1988)[2] Gary A. Prinz, Science 282, 1660(1998)[3] Jagadeesh S. Moodera, Janusz Nowak, Lisa R. Kinder, Paul M. Tedrow, René J. M. van de Veerdonk, Bart A. Smits, Maarten van Kampen, Henk J. M. Swagten, and Wim J. M. de Jonge, Phys. Rev. Lett. 83, 3029(1999)[4] R. Wiesendanger, M. Bode and M. Getzlaff, APPLIED PHYSICS LETTERS 75,124-126(1999)[5] A. Bedyayev, D. Bagrets, A Bagrets and B, Dieny, PHYSICAL REVIEW B 6305,4429(2001)[6] P. LeClair, H. J. M. Swagten, J. T.Kohlhepp, R. J. M. van de Veerdonk, and W. J. M de Jonge, Phys. Rev. Lett. 84, 2933(2000)[7] J. J. Sun and P. P. Freitas, J. Appl. Phys. 85, 5264(1999)[8] Elbio DAGOTTO, Takashi HOTTA, Adriana MOREO, Physics Reports 344(2001) 1-153[9] E. R. Nowak, M. B. Weissman and S. S. P. Parkin, APPLIED PHYSICS LETTERS 174, 600-602(1999)[10] B. Doudin, G. Redmond, S. E. Gilbert and J. P. Ansermet, PHYSICAL REVIEW LETTERS 179, 933-936(1997)[11] P. Seneor, A. Fert, J. L. Maurice, F. Montaigne, F. Petroff and A. Vaures, APPLIED PHYSICS LETTERS 74, 4017-4019(1999)[13] E. Gommert, J. Appl. Phys, 85, 5417(1999)[14] T. K. Nath, R. A. Rao, D. Lavric, and C. B. Eom,Appl. Phys. Lett. 74, 1615(1999)[15] C. J. Lu, and Z. L. Wang, J. Appl. Phys, 88, 4032(2000)[16] M. Mc/cirnacj et.al. Appl. Phys. Lett. 64, 3054(1994)[17] G.C. Xiong et.al. Appl. Phys. Lett. 66, 1427(1995)[18] Z. W. Dong et.al. IEEE Tran. Appl. Superconduc. 7,2173(1997)[29] M. F. Hundley et.al. Appl. Phys. Lett. 67,860(1995)[20] G. Jeffrey Snyder et.al. Phys. Rev. B53, 53(1996)[21] H.T. Hardner et.al. J. Appl. Phys. 81, 272(1997)[22] A. P. Ramirez, J. Phys. Condens. Matter 9, 8171(1997)[23] M. Julliere. Phys. Lett. 54A, 225(1975)[24] Clarenece Zener, Phys. Rev. 81, 440(1951)[25] J. M. D Coey, M. Viret, L. Ranno, Phys. Rev. Lett. 75, 3910(1995)[26] John B. Goodenough, J. Appl. Phys. 81, 5330(1997)[27] S. M. Dunaevskii, Physics of the Solid State 40,1687(1988)[28] A. J. Millis, Boris I. Shraiman, and R. Mueller, PHYSICAL REVIEW LETTERS 77, 175(1996)[29] J. S. Moodera, L. R. Kinder, T. M. Wong, and R. Meservey, Phys. Rev. Lett. 74, 3273(1995)[30] Patric W. Anderson, Phys. Rev. 100, 675(1995)[31] A. J. Millis el.al. Phys. Rev. Lett. 74, 5144(1995)[12]磁性物理學，齊卡茲尼著，張煦、李學養譯[32]吳尉壯，中山大學物理所，九十年碩士論文