Growth, Crystalline Structure and Spin Reorientation Transition in Ultrathin CoxNi1-x/Cu3Au(100) Alloy films
| Autor: | Bo-Yao Wang, 王柏堯 |
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| Rok vydání: | 2004 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 92 The magnetic ultrathin CoxNi1-x/Cu3Au(100) alloy films with x≦12% are prepared for the investigation of spin-reorientation transition (SRT). The growth, crystalline structure, magnetism of CoxNi1-x/Cu3Au(100) grown at 300 K are measured using medium energy electron diffraction (MEED), scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and magneto-optical Kerr effect (MOKE). Due to the more strain energy of crystalline structure in CoxNi1-x/Cu3Au(100), the relaxation of crystalline structure proceeds gradually after 8 ML. The vertical interlayer distance relaxes from 1.66 Å to 1.76 Å as the thickness increasing from 8 to 16 ML, which can be fitted well by a simple relaxation model based on the dislocation with thickness. The structure remains the same irrespective of the variation in alloy composition. The boundaries of SRT are fitted well by a phenomenological model based on magneto-elastic anisotropy. The first SRT is attributed to the accumulation of strain energy with thickness, and the second SRT is mainly caused by the strain relaxation. Increasing of the Co concentration causes significant reduction of the thickness region of perpendicular magnetization. This is due to the Co induced change of magneto-elastic coefficient. A stronger moment of Co, which causes a larger demagnetization field, also contributes to the reduction of the region of perpendicular magnetization. Besides, the relaxation of crystalline structure of Ni/Cu3Au(100) grown at 100 K proceeds gradually after 6 ML. Ni/Cu3Au(100) grown at 100 K, and shows the canted magnetization below 8 ML and above 13 ML. As compared to the films grown at room temperature, a possible explanation to the canted magnetization is attributed to the rougher surface and the different strain relaxation process. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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