NiO/Co/Cu/Co/Cu/Co/NiO對稱式自旋閥單晶異向性之探討

• Main Author: 蔡傳博
• Other Authors: G.Chern
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/37293342218672980725

碩士 === 國立中正大學 === 物理系 === 90 === A series of symmetrical spin valve sandwiches of NiO/Co/Cu/Co/Cu/Co/NiO on single crystal substrates including MgO(100),(110),(111) orientations are fabricated by molecular beam epitaxy, and we measure the hysteresis loops and the MR loops. Besides we field cool the sandwiches and do the same measurement. In the process of measurement, we applied a field in plane, and change angles between applied field and the samples. In (100) orientation we observed, the MR ratio of the as grown sample are about 1%~1.7%, the pinned layer coercivity (Hcp) are about 172Oe~215Oe, and the MR ratio of the field cooled sample increase to 2.7%~3.2%, the Hcp also increase about 215Oe~280Oe; In (110) orientation we observed, the MR ratio of the as grown sample are about 1.4%~5.4%, the Hcp are about 285Oe~752Oe, and the MR ratio of the field cooled sample the maximum MR ratio decrease to 4.5% and the minimum ratio increases to 1.9% , the Hcp also increase about 529Oe~ 1500Oe; In (111) orientation we observed, the MR ratio of the as grown sample are about 2.2%~5.4%, the Hcp are about 252Oe~517Oe, and the MR ratio of the field cooled sample increases to 5.6%~ 3.3%, but the Hcp do not change with changing angle, its amount is about 300Oe. From these data we can get some result obviously: orientations have very large effect on single crystalline spin valve sandwiches, and the process of field cooling have different effect for (100), (110), (111) orientations. In addition, we observed the uniaxial symmetry on (100), (110), (111) orientations, it applied exchange anisotropy play an important role, and crystalline anisotropy play a minor role for the total anisotropy energy.