| Summary: | 碩士 === 國立臺灣師範大學 === 物理學系 === 94 === Experiments were performed in situ in a stainless ultrahigh vacuum (UHV) chamber. In situ magneto-optical Kerr effect (MOKE) was used to study the magnetic properties of the
system.
I study the magnetic properties of ultrathin Co films on Pt(111) with Ni buffer layers. We prepare dCo Co/1 ML Ni/Pt(111), and the Kerr signals measured at room temperature. The polar and longitudinal Kerr signal was not exist for 0 ~ 3 ML Co/1 ML Ni/Pt(111). The easy axis of the magnetization for 4＆5 ML Co/ Pt(111) is in-plane. We find the same result, when dCo Co/1 ML Ni/Pt(111) was prepare at 450K, and the Kerr signals measured at 450K or at room temperature. If we prepare dCo Co/1 ML Ni/Pt(111) at RT, and the Kerr signals measured at 450K. The easy axis of the magnetization for 1 ML Co/ Pt(111) is out-of-plane. The polar and longitudinal Kerr signal was not exist for 2＆3 ML Co/1 ML Ni/Pt(111). The easy axis of the magnetization for 4＆5 ML Co/ Pt(111) is in-plane. The variation of AES of 1 ML Co/1 ML Ni/Pt(111) as a function of sample temperature. We find the mixing of Ni and Co layers occurs at 420K. The formation of Co-Pt alloy causes the perpendicular magnetic anisotropy.
I also study the magnetic properties of ultrathin Ni films on Pt(111) with Co buffer layers. The easy axis of the magnetization for 1 ML Co/ Pt(111) is out of plane. We were surprised that only the polar Kerr signals were observed when dNi 24 ML. Studies of the magnetic properties showed that the easy axis of the magnetization changed from the cant to the out-of-plane direction when the Co buffer layer was inserted on Ni/Pt(111).
After different temperature annealing, cause the different competition alloy. The competition in the alloy formations between Co-Pt and Ni-Pt in the Co/Ni/Pt(111) and Ni/Co/ Pt(111) system is also interesting, cause the different magnetic properties. I also try to understand that.
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