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Collaborative Research: Frustration, glassiness and spin liquids: from dirty to pristine materials

合作研究：挫败感、玻璃质和旋转液体：从脏材料到原始材料

基本信息

批准号：
2218130
负责人：
Arthur Ramirez
金额：
$ 53.36万
依托单位：
University of California-Santa Cruz
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-09-01 至 2026-08-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2218130&HistoricalAwards=false
关键词：
Collaborative Research Frustration glassiness spin

项目摘要

Non-technical abstractCurrently, immense global experimental efforts are directed at finding quantum spin liquids (QSLs), a theoretically-predicted state of magnetic materials in which the spins, or atom-size bar-magnets, exhibit liquid-like properties down to the lowest possible temperatures. QSLs can be efficiently used to create quantum bits, “qubits”, as they can store information encoded simultaneously in the states of multiple spins, and hence protected from local noise. Thus, QSLs hold great promise as a platform for future computing and communication technology. A present barrier to their realization is randomly located impurities and defects that can convert a QSL into another state of matter, “spin glass”, in which the spins freeze in random orientations, similar to how silicon atoms possess random positions in window glass. This research investigates the effect of impurities and defects on the fundamental properties of geometrically frustrated magnets, the largest class of materials in which QSLs are being sought. Through systematically controlling defects during material synthesis, and theoretically modeling the resulting behavior, the team is laying the foundations for future engineering of QSL-based devices. The broader impacts of this research are both the development of synthesis methods for reducing defects in crystalline specimens and the theoretical understanding that will inform future processing endeavors. In addition, the research helps train junior researchers directly involved in the project, as well as the broader community through instructional media and data that are accessible on open-source platforms such as the NSF’s Crystal Sample Archive. Technical abstractThis research is a combined experimental and theoretical effort to systematically investigate the effect of quenched disorder on collective magnetism in geometrically frustrated (GF) materials and to determine the synthesis barriers to obtaining pure materials. The research includes synthesis of materials spanning the entire range of spin density from dilute spin, to concentrated disordered spins, to dilute impurities, en route to ultra-pure materials. Part of the work uses quenched disorder as a probe of fundamental properties of GF magnetism. The measurements of the thermodynamic properties of disordered GF materials aim to uncover microscopic Hamiltonians of GF systems, reveal possible universality classes of disorder-induced spin-glass transitions, investigate the origin of the recently discovered “hidden energy scale” in these systems and reveal the nature of elementary excitations in them. The work includes theoretical calculations of the thermodynamic manifestations of the microscopic details of the Hamiltonians, exploring the interplay of different types of disorder in GF media and constructing models for the “hidden energy scale” and the behavior of heat capacity in GF magnets, which is used to make prediction and explain experimental data. Part of this research may result in obtaining materials that exhibit strong quantum-spin-liquid behavior and demonstrating the irrelevance of quenched disorder in them.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要目前，全球大量的实验工作都是针对寻找量子自旋液体(QSL)，这是一种理论上预测的磁性材料的状态，在这种状态下，自旋或原子大小的条形磁体在可能的最低温度下表现出类似液体的性质。QSL可以有效地用于创建量子比特，即“量子比特”，因为它们可以存储同时以多个自旋的状态编码的信息，从而防止局部噪声。因此，QSL作为未来计算和通信技术的平台前景广阔。目前它们实现的障碍是随机定位的杂质和缺陷，这些杂质和缺陷可以将QSL转换为另一种物质状态--自旋玻璃，在这种状态下，自旋以随机方向冻结，类似于硅原子在窗户玻璃中具有随机位置。这项研究调查了杂质和缺陷对几何受挫磁体基本性质的影响，几何受挫磁体是寻找QSL的最大类别的材料。通过系统地控制材料合成过程中的缺陷，并对产生的行为进行理论建模，该团队正在为基于QSL的设备的未来工程奠定基础。这项研究的更广泛的影响既是为减少晶体样品中的缺陷而开发的合成方法，也是为未来的加工努力提供指导的理论理解。此外，这项研究还帮助培训直接参与该项目的初级研究人员，以及更广泛的社区，通过可在NSF的水晶样本档案等开源平台上访问的教学媒体和数据。这项研究是一项实验和理论相结合的工作，旨在系统地研究淬火无序对几何受阻(GF)材料集体磁性的影响，并确定获得纯材料的合成势垒。这项研究包括合成整个自旋密度范围的材料，从稀薄自旋到集中无序自旋，再到稀释杂质，再到超纯材料。部分工作使用猝灭无序作为对GF磁性基本性质的探索。无序玻璃纤维材料热力学性质的测量旨在揭示无序玻璃纤维体系的微观哈密顿量，揭示无序诱导的自旋玻璃化转变的可能普适性类，研究最近发现的“隐含能级”的起源，并揭示它们中元素激发的本质。这项工作包括对哈密顿量微观细节的热力学表现的理论计算，探索不同类型的无序在GF介质中的相互作用，以及建立用于预测和解释实验数据的GF磁体中的“隐藏能量标度”和热容行为的模型。这项研究的一部分可能会导致获得表现出强烈的量子自旋-液体行为的材料，并证明其中的猝灭无序无关性。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。