Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/16997
標題: study of physical properties in the colossal magnetoresistive Materials La0.7Ba0.3Mn1-xFexO3(x=0.02~0.2)
La0.7Ba0.3Mn1-xFexO3(x=0.02~0.2)龐磁阻材料 物理性質之研究
作者: Wei, Jung-Ting
魏榮廷
關鍵字: 鈣鈦礦
perovskite
龐磁阻
雙交換作用
超交換作用
飽和磁矩
鐵磁性
自旋波
複合式偏極子模型
楊-泰勒偏極子
鐵磁轉換溫度
colossal magnetoresistance
double-exchange interaction
superexchange interaction
saturation magnetization
ferromagnetic
spin wave
Composite polaron model
Jahn-Teller polaron
ferromagnetic transition temperature
出版社: 物理學系所
引用: [1]R.von Helmolt et al.,Phys. Rev. Lett.71,2331(1993) [2]“磁性物理學” 電子工業出版社 [3]“磁性物理學” 聯經出版社 [4]P.W. Andeson ,Phys. Rev. 79,350(1950) [5]C.Zener,Phys. Rev,81,440(1951) [6]H.A.John ,E.Teller, Proc. R.Soc. London A,166.220,(1937) [7]A.J.Millis ,B.i.Shraiman, Phys. Rev. Lett.74.25(1995) [8]H. Y. Hwang, S-W. Cheong, P. G. Radaelli, M. Marezio, and B. Batlogg, Phys. Rev. Lett. 75, 914 (1995) [9]L.J.Zou,H.Q.Lin,Q.Q.Zheng,J App. Phys.87.7362 [10]物理雙月刊 二十二捲六期 林昭吟著 [11]L.K.Leung, A.H.Morrish and B.J.Evans Phys. Rev. B 13 4069 (1976) [12]J.Cai, C.Wong,B.Shen,J.Zhao and W.Zhan 1997 Appl.Phys. Lett.71 1727 (1997) [13]S.L.Young , Y.C.Chen, H.Z. Chen, J APP. Phys 91,10, (2002) [14]K.H.Ahn,X.W.Wu,K.Liu,and C.L.Chien Phys. Rev.B 54 21 (1996) [15]J.M.Liu ,T.Yu ,Q Hung J.Li ,J.Phys 14 L141~147 (2002) [16]P,Schiffer,A.P. Ramirez,W. Bao and S.W. Chong Phys. Rev. Lett. 75.18(1995)
摘要: The magnetic and electronic properties of the perovskite system La0.7Ba0.3Mn1-xFe xO 3 (x=0~0.3) have been investigate by measurements of magnetization ,resistivity and magnetoresistance .Powder x-ray diffraction patterns show the distance induced by Mn-site substitution is not obvious due to the similar radius of Mn an Fe .The transport properties show the resistance increases with Fe3+ increase and for x≦0.1 the insulator-metal transition temperature shifts to low temperature due to Fe not play a part in Double-exchange mechanism and suppress Mn3+/Mn4+ interaction.The resistance above the transition temperature can be fited by small polaron model. The magnetoresistance significantly enhance by Fe-doping increase.Values of temperature dependence of magnetization indicate the ferromagnetic double-exchange interation is gradually substituted by antiferromagnetic superexchange interation .The purpose of this thesis is to clear up the role functions of all elements in these compounds. Based on the knowledge of these compounds if would be helpful to control physical mechanism and improve the characteristics on prepaing their devices.
本研究是針對La0.7Ba0.3MnO3利用其具有鈣態礦結構及龐磁阻現象, 藉由Fe3+離子摻雜取代Mn3+離子,對原子的取代來觀察磁性、電性和磁阻比所造成的影響。研究結果顯示,可知Mn位置Fe3+離子被取代造成的晶格扭曲不明顯,由X光繞射圖判讀顯示隨著摻雜量增加結構並沒有改變,因錳、鐵的離子半徑差異不大。而在傳導性中當x≦0.1,在低溫時,隨著溫度上升,自旋波被激發越容易受到散射,造成電阻上升,呈現金屬性;而在高溫時,隨著溫度不斷上升,被束縛的電子獲得跳躍能量越大,電阻率也開始下降,呈現絕緣性。同時利用複合極化子(composite polaron)模型和自旋相關傳導特性,來做電傳導的分析。得到Fe3+離子的摻雜增加,活化能增加,也相對應提高在零場電阻值。在磁性方面,從溫度改變的磁化強度也顯示Fe3+離子的摻雜增加,使得Mn-O-Fe反鐵磁超交換作用的總含量增加,導致鐵磁性逐漸減弱,磁矩間的作用力也相對減弱,易受熱效應影響,導致鐵磁轉換溫度的降低。所以本論文的研究在藉由元素的摻雜以釐清化合物中元素所判演的角色,進一步瞭解此材料的特性以期許將來在製造元件可以充分掌握其物理機制,同時在特性改善上有所依據。
URI: http://hdl.handle.net/11455/16997
其他識別: U0005-0708200714175300
文章連結: http://www.airitilibrary.com/Publication/alDetailedMesh1?DocID=U0005-0708200714175300
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