Magnetic microstructure and range of critical magnetic correlations in nanocrystalline gadolinium

纳米晶钆的磁性微观结构和临界磁关联范围

• 批准号: 24982846
• 负责人: Professor Dr. Andreas Michels
• 金额: --
• 依托单位: Laboratory for the Physics of Advanced Materials
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2013-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/24982846?language=en
• 关键词: Magnetic; microstructure; range; critical; magnetic

We will study the influence of internal interfaces (grain and phase boundaries) on the Curie transition and on the magnetic microstructure of nanocrystalline bulk gadolinium and nanocrystalline gadolinium alloys. High-quality nanocrystalline bulk gadolinium samples can now be prepared by the inert-gas condensation technique, and their magnetic properties will be investigated by means of magnetometry, specific-heat measurements, neutron diffraction, and in particular by measurements using magnetic small-angle neutron scattering on the low-capturing isotope 160gadolinium. Magneticfield dependent small-angle neutron scattering in conjunction with the theory of micromagnetics is a novel approach which allows one to determine the set of intrinsic interaction parameters of a ferromagnet such as exchange constant, anisotropy field, stray field, and a characteristic length of spin misalignment. By alloying nanocrystalline gadolinium with the highly anisotropic rare-earth metal terbium, we aim at tailoring increasing magnetic anisotropy and study its effect on the magnetic interactions. Furthermore, we propose to study the effect of grain-boundary chemistry on the magnetic behavior by alloying nanocrystalline gadolinium with the nonmagnetic element tantalum which exhibits a strong tendency to interfacial segregation. In particular, by varying the tantalum interfacial excess concentration, we are able to study the mechanism of exchange coupling across grain boundaries.

我们将研究内部界面（晶粒和相界）对纳米晶块体钆和纳米晶钆合金居里转变和磁性微观结构的影响。利用惰性气体冷凝技术可以制备高质量的纳米晶块体钆样品，并将通过磁强计、比热测量、中子衍射，特别是利用低捕获同位素160钆的磁小角中子散射测量来研究其磁性能。磁场相关的小角中子散射与微磁学理论相结合是一种新的方法，它允许人们确定铁磁体的内在相互作用参数集，如交换常数、各向异性场、杂散场和自旋失调的特征长度。通过将纳米晶钆与高各向异性稀土金属铽合金化，旨在剪裁增大的磁性各向异性，并研究其对磁性相互作用的影响。此外，我们提出通过将纳米晶钆与具有强烈界面偏析倾向的非磁性元素钽合金化来研究晶界化学对磁性行为的影响。特别是，通过改变钽界面过量浓度，我们可以研究跨晶界交换耦合的机制。