Investigating complex, marginal and exotic magnetic ordering in rare-earth based materials

研究稀土基材料中复杂、边际和奇异的磁序

• 批准号: RGPIN-2020-04211
• 负责人: Ryan, Dominic
• 金额: $ 1.75万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739508
• 关键词: Investigating; complex; marginal; exotic; magnetic

Three primary themes will be the focus of the next five years of my research program: (1) Discovering new technetium-based intermetallic compounds (2) Exploring exotic magnetic ordering in europium-based intermetallic compounds (3) Investigating valence instabilities and magnetic ordering in ytterbium-containing systems. The first theme will involve the creation of a new facility to handle technetium and prepare single-crystal samples using it. Technetium is remarkable. It is the lightest element that lacks a stable isotope. Indeed it is the only radioactive element in the main s,p,d block of the periodic table. It sits directly below manganese and shares its half-filled d5 electronic configuration, opening the possibility of 4d magnetism. Some compounds, notably oxides and halides are known to be magnetic, and some metallic systems are superconducting, but very few of its intermetallic compounds have ever been prepared and fewer still have been investigated for magnetism. While it unlikely that any compound of technetium will see direct applications (its 6-day parent 99Mo is a key medical isotope, used in the diagnosis of heart problems and cancers) the knowledge gained will lead to a better understanding of magnetic systems. The second theme is Eu-based materials. Recent theoretical and experimental discoveries of topological semi-metals (TSM) and Weyl semi-metals are opening exciting frontiers of science at the boundaries of materials science and magnetism. The hope is that understanding the basic principles of TSM and WSM systems will deliver new materials platforms for photodetection, spintronics and quantum computing. I will be working with teams from the AmesLab in Iowa studying a wide range of Eu-based materials using Mössbauer spectroscopy and neutron diffraction. We have already identified some materials that have potential as magnetic refrigerants offering greenhouse gas (GHG) free refrigeration and have several more systems that we are studying. The third theme is Yb-based materials. Ytterbium exhibits a significant valence instability that leads to a rather fragile magnetic moment. We will combine 170Yb Mössbauer spectroscopy with neutron diffraction to investigate these systems. In addition, several Yb compounds show promise for thermoelectric power generation (direct conversion of waste heat into electricity). Many rely on the presence of "rattlers", weakly bound rare-earth or alkaline earth metals. There are few direct ways to investigate these almost-isolated atoms, however the digital time-differential perturbed angular correlation (TDPAC) spectrometer that we designed and built is perfect for the project. We will work with teams from Italy and the US on these projects.

三个主要主题将成为我未来五年研究计划的重点：（1）发现新型锝基金属间化合物（2）探索铕基金属间化合物中的奇异磁序（3）研究含镱系统中的价态不稳定性和磁序。第一个主题将涉及创建一个新设施来处理锝并使用它制备单晶样品。锝是非凡的。它是最轻的元素，缺乏稳定同位素。事实上，它是周期表主 s、p、d 区中唯一的放射性元素。它位于锰的正下方，并具有半填充的 d5 电子配置，开启了 4d 磁性的可能性。一些化合物，尤其是氧化物和卤化物，已知具有磁性，而一些金属系统具有超导性，但其金属间化合物的制备方法很少，并且对其磁性进行研究的金属间化合物也较少。虽然任何锝化合物不太可能得到直接应用（其 6 天母体 99Mo 是一种关键的医用同位素，用于诊断心脏问题和癌症），但所获得的知识将有助于更好地理解磁系统。第二个主题是欧盟材料。最近拓扑半金属（TSM）和外尔半金属的理论和实验发现正在材料科学和磁性的边界上开辟令人兴奋的科学前沿。希望了解 TSM 和 WSM 系统的基本原理将为光电探测、自旋电子学和量子计算提供新的材料平台。我将与爱荷华州 AmesLab 的团队合作，利用穆斯堡尔谱和中子衍射研究各种铕基材料。我们已经确定了一些有潜力作为磁性制冷剂提供无温室气体 (GHG) 制冷的材料，并且我们正在研究更多系统。第三个主题是镱基材料。镱表现出显着的价态不稳定性，导致相当脆弱的磁矩。我们将结合 170Yb 穆斯堡尔谱和中子衍射来研究这些系统。此外，几种镱化合物显示出用于热电发电（将废热直接转化为电能）的前景。许多依赖于“响尾蛇”的存在，即弱结合的稀土或碱土金属。研究这些几乎孤立的原子的直接方法很少，但是我们设计和建造的数字时微分扰动角相关（TDPAC）光谱仪非常适合该项目。我们将与来自意大利和美国的团队合作开展这些项目。