Exotic Magnetic Ground States and Ground State Selection in Quantum Materials

量子材料中的奇异磁基态和基态选择

• 批准号: RGPIN-2019-07084
• 负责人: Gaulin, Bruce
• 金额: $ 6.92万
• 依托单位: McMaster 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=739300
• 关键词: Exotic; Magnetic; Ground; States; State

The ground states of most magnetic materials, and all magnetic materials which are well understood, are characterized by long range order and conventional elementary excitations, such as spin waves. We are specifically interested in families of new magnetic materials, where this isn't the case; that is where a disordered low temperature phase can persist due to the presence of very strong spin fluctuations. This is a very topical area of contemporary condensed matter research as it is widely believed that if a conventional ordered state can be suppressed at low temperatures, it opens a window for an exotic ground state to be manifest.  Appropriate quantum disordered states are thought to possess qualitatively new and remarkable physical properties, such as delocalized quantum spin excitations, that may provide a platform for quantum computation. Strong spin fluctuations can be encouraged in three ways in magnetic materials: magnetic moments can decorate local geometries (typically based on triangles and tetrahedra) in solids which are incompatible with a simple ordered state - this is referred to as geometrical frustration; S=1/2 and effective S=1/2 magnetic moments, which support extreme quantum fluctuations, can be made to decorate the lattice; and finally the magnetic lattice can be effectively two or one dimensional due to a three dimensional crystal structure which is made of a stacking of magnetic planes, or a bunching together of magnetic chains.  This proposal seeks to explore new magnetic materials which do precisely this. By carrying out advanced characterization, primarily with new neutron and x-ray scattering techniques we aim to elucidate the nature of the exotic ground states which ensue in such materials, such that the principles that underlie the novel phenomena they display can be fully understood. This proposal seeks to carry out programs of neutron scattering measurements on several families of exotic magnetic materials that we will grow in single crystalline, polycrystalline and epitaxial thin film form. We are in the midst of a renaissance in the capabilities available to carry out forefront inelastic neutron scattering.  The net result is that new neutron scattering instrumentation provides qualitatively different, and much more comprehensive, information on materials than was possible six years ago. This proposal seeks to apply this new infrastructure to several topical problems related to exotic magnetic ground states in new materials. A crucial component and starting point for the themes of this proposal is a program of sophisticated materials preparation and crystal growth which will provide new magnetic materials in appropriate forms. We are exceptionally well positioned, both with respect to our capacity to produce materials of interest, and with respect to access and expertise associated with the new neutron scattering infrastructure, to make real progress in this very topical area of condensed matter physics.

大多数磁性材料以及所有众所周知的磁性材料的基态都具有长程有序和传统基本激发的特征，例如自旋波，我们对新磁性材料系列特别感兴趣，但这不是主要的。情况；即由于存在非常强的自旋涨落，无序低温相可以持续存在，这是当代凝聚态物质研究的一个非常热门的领域，因为人们普遍认为，如果可以在低温，为异域风情打开了一扇窗适当的量子无序态被认为具有全新且显着的物理特性，例如离域量子自旋激发，这可以通过三种方式在磁性材料中提供强自旋涨落的平台。 ：磁矩可以装饰固体中与简单有序状态不相容的局部几何形状（通常基于三角形和四面体） - 这被称为几何挫败（S=1/2）并且有效；可以使支持极端量子涨落的S=1/2磁矩来装饰晶格，并且由于由磁性平面堆叠而成的三维晶体结构，最终磁晶格可以有效地是二维或一维的； ，或聚集在一起的磁链，该提案旨在探索新的磁性材料，通过进行高级表征，主要是使用新的中子和 X 射线散射技术，我们的目标是阐明其本质。该提案旨在对我们将在其中生长的几个奇异磁性材料家族进行中子散射测量计划。单晶、多晶和外延薄膜形式我们正处于可进行前沿非弹性中子散射的能力的复兴之中，最终的结果是新的中子散射。该提案旨在将这种新的基础设施应用于与新材料中奇异磁性基态相关的几个主题问题，这是该研究的关键组成部分和起点。该提案的主题是复杂的材料制备和晶体生长计划，该计划将提供适当形式的新型磁性材料，无论是在我们生产感兴趣材料的能力方面，还是在相关的获取和专业知识方面，我们都处于非常有利的地位。与新的中子散射基础设施，在凝聚态物理这个非常热门的领域取得真正的进展。