磁性複合薄膜中垂直磁矩對介電性質提升之研究

Abstract

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(Fe54Pt46)與鈦酸鋇(BaTiO3)的磁性複合薄膜。以L10相之鐵鉑合金薄膜作為磁性複合薄膜的覆蓋層(Capping layer)，當面心正方(Face center tetragonal, FCT)的鐵鉑合金薄膜序化度為0.8319時，薄膜內部提供的垂直磁矩透過磁電效應(Magnetoelectric effect)提升鈦酸鋇薄膜於立方晶相時的介電係數。將垂直序化之鐵鉑合金整合於鈦酸鋇陶瓷薄膜電容，可將立方晶相的鈦酸鋇薄膜介電係數在1kHz量測頻率時提升至726。在FePt/MgO/BaTiO3/Pt/Ti/SiO2/Si的磁性金屬-絕緣體-非磁性金屬(MM-I-NM)結構中，可在室溫環境中發現327%(1kHz)、200%(2kHz)、79%(4kHz)的磁電容效應(Magnetocapacitance)。此外，以鐵鉑合金作為覆蓋層的磁性複合薄膜在I-V曲線中擁有較Pt/BaTiO3/Pt/Ti/SiO2/Si非磁性MIM結構低的漏電流。

In this thesis, we used magnetron sputtering deposition technique to deposit the magnetic complex thin film that integrates Fe54Pt46 into BaTiO3 thin film capacitor. The magnetoelectric effect arising from the FePt/BaTiO3 interface enhances the relative dielectric constant of BaTiO3 due to the strong perpendicular magnetic anisotropy of FePt, when the order parameter of FePt was 0.8319. When the magnetic complex thin film integrates FePt into cubic BaTiO3 thin film ceramic capacitor, the relative dielectric constant was enhanced to 726 in 1kHz measuring frequency. In magnetic metal/insulator/non-magnetic metal structure, FePt/MgO/ BaTiO3/Pt/Ti/SiO2/Si, we find 327%, 200% and 79% room temperature magnetocapacitance effect in 1kHz, 2kHz and 4kHz measuring frequencies respectively. Furthermore, the leakage current of the magnetic complex thin film capacitor is lower than the Pt/BaTiO3/Pt/Ti/SiO2/Si non-magnetic MIM structure in I-V curve.