Specific local relaxation and magnetism in mass-selected CoPt nanoparticles
Specific local relaxation and magnetism in mass-selected CoPt nanoparticles
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DOI：
10.1140/epjb/e2013-30644-0
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
V. Dupuis;N. Blanc;L. E. Díaz-Sánchez;A. Hillion;A. Tamion;F. Tournus;G. Pastor
中科院分区：
文献类型：
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作者：
V. Dupuis;N. Blanc;L. E. Díaz-Sánchez;A. Hillion;A. Tamion;F. Tournus;G. Pastor
我们报告的精细定量磁矩的大小选择的直径为3 nm的CoPt团簇在Co和Pt-L2，3边缘。结合同步辐射ESRF光束线的高光子通量和化学选择性，我们研究了尺寸效应对镶嵌在碳基体中的CoPt团簇的局域结构和磁性的影响。一方面，通过Pt-L边扩展X射线吸收精细结构（EXAFS）实验和Co-K边实验的模拟，我们确定了Co-Co，Co-Pt和Pt-Pt的第一壳层配位数和平均原子距离，与最近的VASP从头计算结果一致。另一方面，X-射线磁性圆二色性（XMCD）的调查已经揭示了一个显着增加的Co和Pt的磁矩的化学有序的CoPt簇相比，散装值，而退火样品的磁各向异性能（MAE）的两倍，制备的样品，但一个数量级小于预期的L10 CoPt散装。
We report the refined quantitative magnetic moments of size-selected 3 nm in diameter CoPt clusters at both Co and Pt-L2, 3edges. By combining the high photon flux and the chemical selectivity of the synchrotron radiation delivered on ESRF beam lines, we have studied size effect on the local structure and magnetism in CoPt clusters embedded in carbon matrix upon annealing. On one hand, from Pt-L edges extended X-ray absorption fine structure (EXAFS) experiments and simulations associated to previous Co-K edge ones, we have determined the first-shell Co-Co, Co-Pt and Pt-Pt coordination numbers and mean atomic distances in agreement with recent VASP ab initio calculations obtained for L10-like clusters. On the other hand, X-ray magnetic circular dichroism (XMCD) investigations have revealed a significant increase of both Co and Pt magnetic moments for the chemically ordered CoPt clusters compared to the bulk values while the magnetic anisotropy energy (MAE) of annealed samples is twice that of the as-prepared samples, but one order of magnitude smaller than what is expected for the L10CoPt bulk.