磁性電容中不同方向與大小磁矩對介電性質提升之研究

Study of Dielectric Property Enhancement with Different Directions and Sizes Magnetic Moment in Magnetic Complex Thin Film

黃崧芥(Sung-Jie Huang)

指導教授 ： 廖洺漢

國立臺灣大學/工學院/機械工程學研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.00010

摘要

本論文中利用磁控濺鍍沉積技術(Magnetron sputtering deposition)製備整合鐵鉑合金(Fe51Pt49)與鈦酸鋇(BaTiO3)的磁性複合薄膜。以L10相之磁矩平行膜面鐵鉑合金薄膜(矯頑場1421 Oe)、磁矩垂直膜面鐵鉑合金薄膜(矯頑場1276 Oe)及加入銀頂層磁矩垂直膜面鐵鉑合金薄膜(矯頑場14700 Oe)三種擁有不同大小及方向磁矩作為磁性複合薄膜的覆蓋層(Capping layer)，當未加入銀頂層的鐵鉑合金薄膜中磁矩垂直膜面時，薄膜內部提供的磁場透過磁電效應(Magnetoelectric effect)提升鈦酸鋇薄膜於立方晶相時的介電係數。薄膜介電係數最高在1kHz量測頻率時提升至814。可在室溫環境中發現379%(1kHz)、278%(2kHz)、102%(4kHz)的磁電容效應(Magnetocapacitance)。但加入銀頂層雖然會強化磁性薄膜的剩磁與矯頑場等磁性質，卻因為導電性不佳而無法做為電容元件電極。當鐵鉑合金薄膜中磁矩平行膜面時，其複合薄膜在I-V曲線中擁有較磁矩垂直膜面的複合薄膜低的漏電流。

關鍵字

磁電效應 ； 磁電耦合 ； 磁電容效應 ； 鐵鉑合金 ； 鈦酸鋇 ； 垂直序化 ； 高介電係數介電層

並列摘要

In this thesis, we used magnetron sputtering deposition technique to deposit the magnetic complex thin film that integrates Fe51Pt49 into BaTiO3 thin film capacitor. The capping layer of Fe51Pt49 have three different directions and the size of the magnetic moment by annealing and one more Ag capping layer. The magnetoelectric effect arising from the FePt/BaTiO3 interface enhances the relative dielectric constant of BaTiO3 with FePt which has perpendicular magnetic anisotropy and did not add the Ag. When the magnetic complex thin film integrates FePt into cubic BaTiO3 thin film ceramic capacitor, the relative dielectric constant was enhanced to 814 in 1kHz measuring frequency. In magnetic metal/insulator/non-magnetic metal structure, FePt/MgO/ BaTiO3/Pt/Ti/SiO2, we find 379%, 278% and 102% room temperature magnetocapacitance effect in 1kHz, 2kHz and 4kHz measuring frequencies respectively. But we can not use FePt with Ag capping to be the electrode because of it’s poor conductivity. Furthermore, the leakage current of the magnetic complex thin film which has level of anisotropy capacitor is lower than the magnetic complex thin film which has perpendicular anisotropy in I-V curve.

並列關鍵字

magnetoelectric effect ； magnetic coupling ； magnetic capacitance effects ； barium titanate ； vertical ordering ； high dielectric constant of the dielectric layer

參考文獻

[37] Takao Suzuki, Zhengang Zhang, Amarendra K. Singh, Jinhua Yin,Alagarsamy

[46] Naoshi Ikeda, Hiroyuki Ohsumi, Kenji Ohwada, Kenji Ishii, Toshiya Inami, Kazuhisa Kakurai, Youichi Murakami, Kenji Yoshii, Shigeo Mori, Yoichi Horibe, and Hijiri Kito, “Ferroelectricity from iron valence ordering in the charge-frustrated system LuFe2O4, ” Nature, Vol. 436, pp. 1136-1138, May. 2005.

[21] P. Villas, and L. D. Calvert, “Binary Alloy Phase Diagrams, ” American Society For Metals, Vol.1, second printing, 1987.

[16] Da-Fu Cui, Hui-Sheng Wang, Zheng-Hao Chen, Yue-Liang Zhou, Hui-Bin Lu, Guo-Zhen Yang, Kun Ma, Hong Chen, Lin Li, Wei Liu, and Yun Zhang, “Crystallographic and microstructural studies of BaTiO3 thin films grown on SrTiO3 by laser molecular beam epitaxy, ” Journal of Vacuum Science & Technology A, Vol. 2, Issue. 2, Apr. 1997.

Perumal, and Hiroshi Osawa, IEEE Trans. Magn. 41, 555 (2005).