| Summary: | 碩士 === 國立雲林科技大學 === 材料科技研究所 === 97 === In the thesis, the magnetic characteristics of perpendicular magnetic tunnel junction (pMTJ) structures are controlled by varying the relative composition of TbFeCo amorphous alloys. Additionally, the titanium (Ti) is utilized as the protection layer. The magnetic properties, film structures, and magnetoresistance variations are measured by Alternating Gradient Magnetometer (AGM), Transmission Electron Microscope (TEM), Multi-Functional Magnetic Hysteresis Curve Magnetometer, and Current In-Plane (CIP), respectively.
In our experiments, the TbFeCo thin films with low coercivity and low saturation magnetization were successfully fabricated by sputtering. The coercivity of the film, served as free layer of the full pMTJ structure, can be reduced down to 900 Oe. To study the influence of annealing, the films were then annealed at the temperature ranging from 150℃ to 250℃. The results shows that the coercivities of pMTJ structures decreased as increasing the annealing temperature and the squarenesses of hysteresis loops were worse as well. Moreover, the films with higher Tb ratio can retain better magnetic properties after high temperature annealing treatment— the squareness was still over 0.9. However, the perpendicularly anisotropy energy constant (Ku) was reduced from its maximum value 2.38×106 erg/c.c. as the composing ration of Tb increased. Finally, the MR ratio determined by CIP method was approximately 0.06~0.1％.
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