本實驗是將鐵磁性La0.7Sr0.3MnO3(n=∞)及反鐵磁性La0.7Sr1.3MnO4 (n=1)兩種龐磁阻材料混和燒結，藉由掺雜少量反鐵磁性(n=1)，增加晶粒界面上自旋無序對載子的磁散射。以提升載子在混合樣品中的碰撞機會，有效提升磁阻效應。
混合樣品依（La0.7Sr1.3MnO4）x/(La0.7Sr0.3MnO3)1-x配比，以不同莫耳數x=0.1、0.15、0.2、0.3、0.5均勻混合，壓成片狀並以高溫1400℃燒結24小時。混合樣品之XRD圖譜分析，得知214極易與113反應產生327。由SQUID數據分析，327為弱反鐵磁性。電阻(ρ)對外磁場(H)曲線，顯示鐵磁113與反鐵磁327磁特性之交互作用與晶粒邊界數影響低場磁阻之效應。

The sample are prepared by co-sintering the pure 3D ferromagnetic colossal magnetoresistance La0.7Sr0.3MnO3 (113) and the 2D spin-glass magnetic insulator La0.7Sr0.3MnO3•SrO (214) with an ordered 2D magnetic-insulator superstructure. Increase the magnetic scattering and collision probabilities of the carries on the interface of the two kinds of CMR materials. The LFMR is enhanced by the electron scattering between these two phases.
(La0.7Sr1.3MnO4)x / ( La0.7Sr0.3MnO3)1-x composites with x=0.1、0.15、0.2、0.3、0.5 have been fabricated by sintering the mixture of the pure La0.7Sr0.3MnO3 (n=∞) and the La0.7Sr1.3MnO4(n=1) at 1400 for 24 hours. Part of the 113 phase reacted with 214 phase during the 1400℃ annealing process and formed the antiferromagnetic phase , La1-2ySr2+2yMn2O7 (327), with the unknown content, y. The ρ-H curve shows the magnetic interaction between the interface grain numbers of the 113 and 327 affects the effect of the low field magnetoresistance effect.

第一章 簡介..........................................................................................................1~3
第二章 基本理論............................................................................................4~19
2-1 磁阻定義............................................................................................4
2-2 洪德法則(Hund’s Rule)................................................................ 5~6
2-3 軌道角動量凍結................................................................................7
2-4 雙交換機制模型(double exchange model)………….................8~10
2-5 Jahn-Teller distortion..................................................................11~12
2-6 龐磁阻材料介紹........................................................................13~19
2-6-1 LaMnO3 .....................................................................13~14
2-6-2 La1-xSrxMnO3 .............................................................15~16
2-6-3 La1-xSr1+xMnO4 .................................................................17
2-6-4 La2-2xSr1+2xMn2O7 ......................................................18~19
第三章 實驗方法...................................................................................20~29
3-1 樣品製作...............................................................................................20~21
3-2 儀器之介紹................................................................................22~29
3-2-1 X-ray 粉末繞射分析(XRD)...........................................22~23
3-2-2電性量測系統..................................................................24~26
3-2-3超導量子干涉磁量儀(SQUID).......................................27~29
第四章 實驗結果與討論.......................................................................30~43
4-1 X-ray分析................................................................................30~31
4-2 電阻與磁阻量測......................................................................32~34
4-3 定溫掃磁場..............................................................................35~39
4-4 磁性量測..................................................................................40~41
4-5 SEM..........................................................................................42~43
第五章 結論.................................................................................................44
參考資料.........................................................................................45

[1] C. Zener, Phys. Rev. 81, 440 (1951) 82, 403(1951).
[2] A.Urushibara et al.vol 51 14103 (1995) 113
[3] Y.Moritomo et al,Phys. Rev.B 51 3297(1995) 214
[4] K. Ruck et al, Journal of Alloys and Compounds 306 (2000) 151–157
[5] Kubota, M., Fujioka, H., Ohoyama, K., Hirota, K., Moritomo, Y., Yoshizawa, H., Endoh, Y., 1999b. J. Phys. Chem.Solids 60, 1161.
[6] T. G. Perring, G. Aeppli, Y. Moritomo, Y. Tokura, preprint
[7] Yu Lu, X. W. Li, G. Q. Gong, and Gang Xiao,Phys. Rev.B 54 8357 (1996)
[8]宛德福，馬興隆.〝磁性物理學〞，電子科技大學出版社(1994).
[9]戴道生，錢昆明，鐘文定，廖紹彬.〝鐵磁學〞，科學出版社(2000).
[10] A. J. Millis, P. B. Littlewood, and B. I. Shraiman, Phys. Rev. Lett. 74, 5144
[11] A. J. Millis, Boris I. Shraiman, and R. Mueller ,Phys. Rev. Lett. 77, 175 (1996)
[12] E. Dagotto et al. / Physics Reports 344 (2001) 1-153
[13] T. Kimura, Y. Tomioka, H. Kuwahara, A. Asamitsu, M. Tamura, Y. Tokura