添加Ho之La0.67Ca0.33MnO3材料的電性、磁性及磁阻研究

洪舜賢(Shun-hsien Hung)

指導教授 ： 許仁華博士

共同指導教授 ： 林昭吟博士

國立臺灣大學/理學院/物理研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.01842

摘要

摘 要

本實驗嘗試添加順磁性很強Ho離子到La0.67Ca0.33MnO3之中取代La離子，研究添加Ho離子對La0.67Ca0.33MnO3的電性、磁性及磁阻的影響，實驗分塊材及薄膜兩部分。
首先，使用固態反應燒結法(solid reaction technique )來製備La0.67Ca0.33 MnO3塊材，由XDR圖形確定燒結出La0.67Ca0.33MnO3之後再添加Ho，比例由0.2 mol%~2.0 mol%，作一系列的塊材分析研究，發現適量添加Ho (0.2 mol%~0.8 mol%)能提升La0.67Ca0.33MnO3金屬-絕緣相轉換溫度TMI值，最高可提升至280K左右(添加Ho 0.2 mol%)。
其次，燒結添加不同Ho比例的2吋靶材(添加比例由0.2 mol%~0.6 mol%)，利用直流濺鍍方法，將La0.67Ca0.33MnO3薄膜濺鍍於STO(100)基板之上，薄膜厚度約30nm。XRD圖形顯示薄膜沿著基板(n00)方向磊晶，且由rocking curve 知道薄膜磊晶品質良好。最後，發現添加Ho的薄膜，有助於提昇薄膜的金屬-絕緣相間之轉換溫度TMI及居禮溫度TC，在濺鍍薄膜時維持基板溫度600℃下，添加Ho比例約0.4 mol%的薄膜TMI值最高(約280K )，TC值約275K。

關鍵字

龐磁阻

並列摘要

In this experiment we add Ho(0.2~2.0 mol%) to La0.67Ca0.33MnO3 (LCMO) sample, and sputtering thin films . The bulks whose metal-insulator (M-I) transition temperature T MI of Ho-doped bulk samples are enhanced about 15K compared with Ho-free LCMO. Hox-La0.67Ca0.33MnO3 films with x = 0, 0.2, 0.4 and 0.6 % mole of Ho have been prepared by dc magnetron sputter -ing. The thin films were grown on SrTiO3(100) substrates with the substrate temperature at 600℃ and the thickness of the films was about 30nm. It has been found from X-ray diffraction that only superlattice peaks corresponding to (002) and (004) planes are present and the peak positions shift to larger angles as the amount of Ho is increased. Furthermore, the magnetic transition temperature Tc and metal- insulator (M-I) transition temperature TMI are enhanced about 25~50K compared with Ho-free LCMO thin film. The enhancement maximum in x ≒ 0.4 occurs at its ordering temperature around 280K.

並列關鍵字

CMR

參考文獻

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