Incoherent magnetization reversal in Co–Pt nanodots investigated by magnetic force microscopy
Incoherent magnetization reversal in Co–Pt nanodots investigated by magnetic force microscopy
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DOI：
10.1016/j.actamat.2011.04.024
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发表时间：
2011-07
期刊：
影响因子：
9.4
通讯作者：
W. Pei;G. Qin;Yuping Ren;Song Li;T. Wang;H. Hasegawa;S. Ishio;H. Yamane
中科院分区：
文献类型：
--
作者：
W. Pei;G. Qin;Yuping Ren;Song Li;T. Wang;H. Hasegawa;S. Ishio;H. Yamane
利用磁力显微镜（MFM）研究了六方密排Co-Pt纳米点（直径50 nm）阵列的磁化反转行为。通过MFM观测确定了每个点的磁开关场（HSW）和阵列的开关场分布（SFD）。结果表明，MFM图像中的点的对比度强度与其HSW有很强的相关性。平均HSW对外加场方向的角度依赖性偏离了相干旋转模型，并出现了涡旋状的非相干旋转。据推断，纳米点似乎是由一个硬的内核与高磁各向异性和软磁性壳层周围的核心。由于交换耦合作用，这种核壳结构导致磁涡旋状非相干旋转。不同厚度的壳层应导致宽SFD。通过采用交换耦合模型的微磁学模拟证实了这一建议，模拟结果与实验结果吻合较好。
The magnetization reversal behavior of a hexagonal close-packed Co–Pt nanodot (50 nm in diameter) array was studied by magnetic force microscopy (MFM). The magnetic switching field (HSW) of each dot and the switching field distribution (SFD) for the array were determined by the MFM observation. The results show that the contrast intensity of the dots in the MFM image has a strong correlation with itsHSW. The angular dependence of the averageHSWon the direction of the applied field deviates from the coherent rotation model, and appears to reverse by a vortex-like incoherent rotation. It is deduced that the nanodot seems to consist of a hard inner core with high magnetic anisotropy and a soft magnetic shell layer surrounding the core. This core–shell structure results in the magnetic vortex-like incoherent rotation because of an exchange coupling interaction. Shell layers of various thicknesses should result in a broad SFD. This proposal is confirmed by micromagnetic simulation using the exchange coupling model, which is in good agreement with the experimental results.