Effects of Ta underlayer and rotational sputtering method on magnetic properties of FeMn/NiFe films.

• Main Authors: Min-Tzong Jiang, 江旻宗
• Other Authors: 張晃暐
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/h9pysd

碩士 === 國立臺北科技大學 === 機電整合研究所 === 103 === Exchange bias (EB), characterized by the shift of hysteresis loops originated from the interaction between the ferromagnetic (FM) and antiferromagnetic (AFM) layers, has been extensively investigated due to wide applications in advanced spintronic devices and giant magnetoresistance heads. Due to high both exchange anisotropy and blocking temperature, FeMn/NiFe bilayer becomes a commonly used EB system. In the first part of this study, Fe50Mn50/Ni81Fe19/Ta films are prepared on SiO2/Si(100) substrates at room temperature (RT) by sputtering at the external magnetic field of 1 kG induced by NdFeB sintered magnets. The magnetic properties of studied films are optimized by modification of working pressure during deposition of Ta(PTa), thickness of Ta(tTa), and thickness of FeMn(tFeMn). X-ray diffraction results show that the crystallinity of the FeMn(111) layer strongly depends on the PTa, tTa, and tFeMn. All studied films exhibit smooth and flat surface with low root-mean-square roughness below 1 nm due to deposition at RT. Large EB field (Heb) of 122 Oe with very small coercivity (Hc) of 16 Oe is found. In the second part of this study, FeMn/NiFe/Ta films are prepared by different type of rotational sputtering method. Samples prepared by rotational sputtering method show better crystallinity of the FeMn layer. The highest Heb of 173 Oe is obtained by a rotational sputtering method which is about twice larger than 84 Oe obtained by the normal sputtering method. In the third part of this study, when direction of applied field is changed from radial direction to tangent direction, samples prepared at applied field in radial direction exhibited better Heb than as compared to that in tangent direction.