Synthesis and Magnetism of Rare Earth Nanostructures

9424339弗林：我们探索和控制稀土纳米结构的磁性行为。它们是由稀土金属制成的堆叠的薄片，通过分子束外延在厚度和含量上进行定制。块状稀土表现出丰富多样的独特的磁性行为，包括独特的日磁和大的磁致伸缩。建议的研究包括对这些新材料构型的结构、磁性、磁微结构和磁输运的研究。利用中子散射、同步辐射X射线散射、SQUID磁测量和光刻处理结构上的输运测量。特别感兴趣的是：磁性相稳定性和薄膜微结构的控制；新磁性纳米结构的化学合成；界面附近磁性耦合的预测；以及包括涨落和非弹性过程在内的相变动力学。%我们主要研究了分子束表面层沉积法制备的稀土金属磁性纳米结构及其性能。这一受控过程将选定的元素金属以高质量单晶的形式在晶体衬底上逐层组装薄膜，并按设计的连续层化学顺序进行组装。对稀土金属的关注是由对其磁性行为的技术和科学兴趣推动的。我们定制选定结构的能力使我们能够探索原子磁矩之间的相互作用，这些相互作用导致了丰富的各种磁性结构。表层沉积过程通过将薄膜夹紧到衬底以及由此产生的应变和薄膜几何形状对磁性产生控制影响。控制这些材料的磁性行为的能力与使用薄膜磁性器件存储、切换和处理信息的应用有关。***

9424339 Flynn We explore and control the magnetic behavior of rare-earth nanostructures. These are synthesized from rare-earth metals as stacks of sheets, tailored in thickness and content by molecular beam epitaxy. Bulk rare earths exhibit a rich variety of unusal magnetic behavior, including unique helimagnetism and large magnetostriction. The proposed research includes studies of structure, magnetism, magnetic microstructure, and magnetotransport in these novel materials configurations. Use is made of neutron scattering, x-ray scattering with synchrotron radiation, SQUID magnetometry, and transport measurements on lithographically processed structures. Of special interest are: control of magnetic phase stability and thin film microstructure; chemical synthesis of new magnetic nanostructures; prediction of magnetic couplings near interfaces; and transformation dynamics including fluctuation and inelastic processes. %%% We focus on the synthesis and properties of magnetic nanostructures made from rare-earth metals by molecular beam surface layer deposition. This controlled process assembles thin films layer by layer on a crystalline substrate, from selected element metals, in the form of high quality single crystals, with a designed chemical sequence of successive layers. The focus on rare-earth metals is driven by technical and scientific interest in their magnetic behavior. Our abiliity to tailor selected structures allows us to explore the interactions among the atomic magnetic moments that cause a rich variety of magnetic structures. The surface layer deposition process has a controlling influence on magnetism through the clamping of the film to the substrate, and through the resulting strain and thin film geometry. The ability to control magnetic behavior of these materials is of interest in connection with applications to the storage, switching, and manipulation of information using thin film magnetic devices. ***