電洞式(p-type)的(La1-xAx)MnO3 [ A：鹼金屬元素，0≦ x≦1]氧化陶瓷材料由於在外加一磁場時會呈現出龐磁阻的效應而被廣泛的研究；而近年來電子式(n-type)的龐磁阻材料(La1-xTx)MnO3 [ T：四價元素，0≦ x≦1]也陸續被發表。然而這些研究並沒有直接的證據支持成功化合的事實，而是分裂成許\多雜相[1,2,3,4,5]。
本實驗選用電子式的La0.7Ce0.3MnO3 (LCeMO)，經固態反應法燒結而成的靶材，利用X光繞射分析儀以及電性量測後，實驗結果顯示塊材本身含有CeO2的存在，而未成功化合成我們所希望的純相。考慮到摻雜的四價離子Ce4+進入到RMnO3會使部分三價的錳離子(Mn3+)轉變成二價的錳離子(Mn2+)。而Mn2+的離子半徑(0.83Å)遠大於Mn3+的離子半徑(0.645Å)，因此導致錳氧八面體(MnO6)結構的不穩定。於是樣品趨向不同成分的相而不朝我們預期的結構反應。
本實驗利用射頻磁控濺鍍系統先成長一層SrTiO3(c=3.905Å)薄膜於MgO(c=4.216Å)基板上，利用晶格間的strain效應將STO的晶格撐大。而後我們再成長La0.7Ce0.3MnO3薄膜於其上，希望藉由較大的晶格減輕錳氧八面體(MnO6)結構的不穩定，進而成長出我們所期望的純La0.7Ce0.3MnO3相產生。

Hole-doped colossal magnetoresistance (CMR) materials La1-xAxMnO3 (A=alkaline metal, 0≤x≤1) has been extensively studied because of its colossal magnetoresistance (CMR) characteristic in a magnetic field. Recently, many suspicious electron-doped CMR materials have been reported. However, none of these “pure phases” were supported directly by experiment evidences, instead, various impurity phases were found.
The La0.7Ce0.3MnO3 (LCeMO) target forming by a solid state reaction method, after analyzing its crystal structure and electric transport properties, is also found to be decomposed into CeO2 impurity and a La deficient La1-dMnO3 phases. This is believed to because the doped Ce4+ ions transforming the Mn3+ ions to Mn2+ whose larger ionic radius (aMn2+ =0.83Å), comparing to that of Mn3+(0.645Å), makes the MnO6 structure instable. Therefore, instead of forming an instable phase, the sample prefers to decompose into different phases.
In this study, we propose to grow LCeMO films on an in-plane-enlarged STO bottom layer which was grown under a tensile strain on MgO (c=4.216Å) substrate. We found that all as grown films exhibits insulating behavior. Nevertheless, the samples after a rapid thermal annealing process can easily decompose the films into multiphase.

目錄
第一章 簡介…………………………………………………… 01
第二章 基本理論……………………………………………… 03
2-1 物質的磁性……………………………………………… 03
2-1-1 順磁性(paramagnetism)……………………… 05
2-1-2 鐵磁性(ferromagnetism).…..................... 06
2-1-3 反鐵磁性(antiferromagnetism)………………....... 07
2-1-4 抗磁性(diamagnetism)…………………………… 08
2-2 磁阻簡介………………………………………………… 09
2-2-1 常磁阻(Ordinary MR, OMR)…………………… 09
2-2-2 異向磁阻(Anisotropic MR , AMR)……………….. 10
2-2-3 巨磁阻(Giant MR, GMR)……………………….... 10
2-2-4 穿遂磁阻(Tunneling MR, TMR)………………….. 10
2-2-5 龐磁阻(Colossal MR ; CMR)……………….. 11
2-3 雙交換機制模型 (Double exchange mechanism ; DE)… 12
2-4 Jahn-Teller distortion…………………………………….. 15
2-5 電子摻雜龐磁阻材料研究回顧……………………… 17
第三章 實驗方法與儀器原理………………………………… 31
3-1 La0.7Ce0.3MnO3靶材製作……………………………… 31
3-2 射頻磁控濺鍍系統…………………………………… 33
3-3 La0.7Ce0.3MnO3薄膜成長…………………………… 35
3-4 電性量測……………………………………………… 37
3-5 X-ray繞射系統……………………………………… 38
3-6 原子力顯微鏡(Atomic Force Microscope, AFM) ……… 40
3-7 快速熱退火(Rapid Thermal Anneal)…………………… 43
第四章 數據分析與討論…………………………………… 44
4-1 SrTiO3/MgO成長分析………………………………… 44
4-2 La0.7Ce0.3MnO3/SrTiO3/MgO成長分析………… 62
第五章 結論……………………69
References.……………......................................................... 70
附錄………………………………………………………………… 72

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