Synthesis and Magnetism of Rare Earth Nanostructures

我们探索和控制稀土纳米结构的磁性行为。这些材料是由稀土金属制成的片状材料，通过分子束外延技术调整其厚度和含量。块状稀土表现出丰富多样的不寻常的磁性行为，包括独特的helimnetic和大磁致伸缩。提出的研究包括这些新材料结构的结构、磁性、磁微观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磁强计和对光刻加工结构的输运测量。特别感兴趣的是：磁相稳定性和薄膜微观结构的控制；新型磁性纳米结构的化学合成界面附近磁耦合预测；转化动力学包括涨落过程和非弹性过程。研究了用分子束表面层沉积法制备稀土金属磁性纳米结构的合成及其性能。这种受控的工艺在晶体衬底上一层一层地组装薄膜，从选定的元素金属中，以高质量单晶的形式，按照设计的化学顺序连续层。对稀土金属的关注是由对其磁性行为的技术和科学兴趣所驱动的。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，从而产生丰富多样的磁性结构。表面层沉积过程通过将薄膜夹紧到衬底，并通过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的信息存储、开关和操作的应用有关。* * *

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. ***