Magnetism in nanoclusters and cluster-assembled thin films.
Magnetism in nanoclusters and cluster-assembled thin films.
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纳米团簇和团簇组装薄膜中的磁性。
DOI：
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发表时间：
2001
影响因子：
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通讯作者：
C. Binns
中科院分区：
文献类型：
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作者：
C. Binns
越来越多的注意力集中在直径为1-5 nm（约50-5000个原子）的纳米颗粒的磁性行为。在这个尺寸范围内，基本的磁性参数，如每个原子的轨道和自旋磁矩明显偏离体积值，研究团簇解决了介观磁性的基本问题，这是不那么好理解的原子或散装制度。人们也越来越认识到，通过沉积预先形成的纳米团簇而不是原子来构建材料的巨大工业潜力。如果团簇的大小选择和沉积结合原子蒸气的基质材料，它是可能的，以产生颗粒状的薄膜，其中有独立的控制的颗粒尺寸和体积分数。使用这种技术，还可以制造可混溶材料的颗粒混合物。这种前所未有的对薄膜特性的控制程度，为研制具有“工程特性”的新型磁性材料提供了希望。为了充分实现这一潜力，不仅需要更好地了解单个粒子，还需要更好地了解它们如何在密集的组件中相互作用。对纳米团簇和团簇组装材料的磁性行为的理解已经取得了很大的进展。产生自旋和轨道力矩的机制，分别增强了高达36%和200%，相对于孤立的集群中的体积是很好的理解，是磁矩的动力学行为。不太清楚的是观察到的磁各向异性，它通常具有与块体不同的对称性。在致密的组件中，粒子间耦合的性质以及偶极和交换相互作用的相对重要性也需要进一步的研究。
Increasing attention has been focused on the magnetic behavior of nanoparticles with diameters of 1-5 nm (approximately 50-5000 atoms). In this size range fundamental magnetic parameters such as the orbital and spin magnetic moments per atom deviate significantly from bulk values, and studying clusters addresses fundamental problems in mesoscopic magnetism, which is not as well understood as in either the atomic or the bulk regimes. There is also a growing realization of the enormous industrial potential of materials built by depositing preformed nanoclusters instead of atoms. If the clusters are size-selected and deposited in conjunction with an atomic vapor of a matrix material, it is possible to produce granular films in which there is independent control over the particle size and volume fraction. Using this technique, it also becomes possible to make granular mixtures of miscible materials. This unprecendented degree of control over the properties of the films holds the promise of new magnetic materials with "engineered properties." To fully realize this potential requires a greater understanding of not only the individual particles, but also how they interact in dense assemblies. There has been great progress in understanding some aspects of the magnetic behavior of nanoclusters and cluster-assembled materials. The mechanisms that generate spin and orbital moments that are enhanced by up to 36 and 200%, respectively, relative to the bulk in isolated clusters are well understood as is the dynamical behavior of the magnetic moment. Not so well understood is the observed magnetic anisotropy, which often has a different symmetry than the bulk. In dense assemblies, the nature of the interparticle coupling and the relative importance of dipolar and exchange interactions also require further research.