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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714954
• 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.

三个主要主题将是我的研究计划的未来五年的重点：（1）发现新的锝基金属间化合物（2）探索铕基金属间化合物中的奇异磁有序（3）研究含镱系统中的价不稳定性和磁有序。 第一个主题将涉及建立一个新的设施来处理锝，并使用它制备单晶样品。它是最轻的元素，缺乏稳定的同位素。事实上，它是元素周期表中s，p，d主区中唯一的放射性元素。它位于锰的正下方，与锰的半满d5电子结构相同，开启了4d磁性的可能性。一些化合物，特别是氧化物和卤化物是磁性的，一些金属系统是超导的，但很少有金属间化合物被制备出来，更少的是被研究磁性。虽然任何锝化合物都不太可能直接应用（其6天母体99 Mo是一种关键的医学同位素，用于诊断心脏病和癌症），但所获得的知识将有助于更好地了解磁系统。 第二个主题是基于EU的材料。拓扑半金属（TSM）和外尔半金属的最新理论和实验发现在材料科学和磁学的边界上开辟了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。我将与来自爱荷华州的AmesLab的团队合作，使用穆斯堡尔谱和中子衍射研究各种各样的铕基材料。我们已经确定了一些有潜力作为磁制冷剂的材料，提供无温室气体（GHG）制冷，并且我们正在研究更多的系统。 第三个主题是Yb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。我们将结合联合收割机170 Yb穆斯堡尔谱与中子衍射来研究这些系统。此外，几种Yb化合物显示出热电发电（将废热直接转化为电能）的前景。许多依赖于“响尾蛇”（弱结合稀土或碱土金属）的存在。目前还没有直接的方法来研究这些几乎孤立的原子，但是我们设计和建造的数字时间微分扰动角相关（TDPAC）光谱仪非常适合这个项目。我们将与来自意大利和美国的团队在这些项目上合作。