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Controlling unconventional properties of correlated materials by Fermi surface topological transitions and deformations.

通过费米表面拓扑转变和变形控制相关材料的非常规性质。

基本信息

批准号：
EP/P002811/1
负责人：
Joseph Betouras
金额：
$ 44.56万
依托单位：
Loughborough University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2016
资助国家：
英国
起止时间：
2016 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FP002811%2F1
关键词：
Controlling unconventional properties correlated materials

项目摘要

Widespread electronic technologies of the last few decades have been led by perfecting control over response of electrons in materials where interactions between them are essentially weak. This can now be reliably achieved, e.g., in simple metals and semiconductors, by tuning the Fermi surface and the effective electron mass. However, this technology has reached the limit of its potential due to the fundamentally limited range of electronic properties exhibited by such materials. A dramatic breakthrough can be achieved if one establishes reliable control over collective electronic behaviour in systems where strong interactions between electrons give rise to intriguing macroscopic quantum phenomena. Multiferroics, giant magnetoresistance in spintronic materials, electron correlations in polymeric systems, and high-temperature superconductivity are just are a few examples with vast potential for novel applications. A quantum computer, expected to revolutionise the modern world, and well-envisaged in principle, can still not be realised due to the lack of reliably controlled material base. The reason, largely, is that a priori accurate theoretical underpinning of electron correlation physics, which would allow to design desired electronic properties at will, has remained a challenge and is currently missing.In light of very recent developments of new accurate numerical tools for correlated systems, it is extremely timely to use the new methodology to address properties of certain correlated materials of great technological potential, which are currently in the focus of extensive experimental studies. In this project, cutting-edge numerics and advanced analytical techniques will allow us to develop a definitive and quantitative theoretical picture of key effects and mechanisms associated with quantum phase transitions in correlated electron systems, thereby enabling a priori control over the corresponding material properties. Specifically, we propose a comprehensive theoretical study of effects of deformations of the Fermi surface in the correlated regime by changing external parameters and the resulting emergence of new phases with unconventional physical behaviour. Our main goals are to: (i) gain quantitative understanding of the mechanisms and consequences of Fermi surface reconstruction and Lifshitz topological transitions in correlated-electron model systems, especially those with spin orbit coupling, and their relation to instabilities, under changes of chemical composition or magnetic field or application of pressure; (ii) accurately predict properties of specific benchmark materials of great technological importance, which exhibit intriguing behaviour associated with changes of the Fermi surface and are the focus of current experiments, such as strontium ruthenates, strontium iridates, and fermonic superconductors. (iii) make specific proposals for experiments on those materials to test new theories, (iv) ultimately, achieve reliable control over the properties of these classes of correlated materials.This is fundamental research with direct relevance to development of technology since our choice of the benchmark materials covers a wide range of potential applications. Superconducting SrRu2O4 is expected to harbour the Majorana bound states, making it a candidate for realising qubits of topological quantum computers. Strontium iridates feature a delicate interplay between spin-orbit coupling and Mott physics, which can lead to new-generation spintronic devices, while control over properties of superconductors under pressure, will open new avenues for the superconducting industry.

在过去的几十年中，广泛的电子技术已经通过完善对材料中电子的响应的控制而被引导，其中它们之间的相互作用基本上是弱的。这现在可以可靠地实现，例如，在简单金属和半导体中，通过调整费米表面和有效电子质量。然而，由于这种材料所表现出的电子性质的范围从根本上受到限制，这种技术已经达到了其潜力的极限。如果在电子之间的强相互作用引起有趣的宏观量子现象的系统中建立对集体电子行为的可靠控制，就可以实现戏剧性的突破。多铁性、自旋电子材料中的巨磁电阻、聚合物系统中的电子相关性和高温超导性只是具有巨大应用潜力的几个例子。量子计算机，预计将彻底改变现代世界，并在原则上设想良好，仍然无法实现，由于缺乏可靠的控制材料基础。其原因主要是，电子关联物理的先验精确理论基础，这将允许随意设计所需的电子特性，仍然是一个挑战，目前还没有。鉴于最近发展的新的精确数值工具的相关系统，这是非常及时的使用新的方法来解决某些相关材料的性质的巨大技术潜力，这是目前广泛实验研究的焦点。在这个项目中，尖端的数值和先进的分析技术将使我们能够开发一个明确的和定量的理论图片的关键效应和相关的电子系统中的量子相变相关的机制，从而实现对相应的材料性能的先验控制。具体而言，我们提出了一个全面的理论研究的费米面的变形的影响，在相关制度，通过改变外部参数和由此产生的新阶段的出现与非常规的物理行为。我们的主要目标是：（i）对相关电子模型系统，特别是具有自旋轨道耦合的相关电子模型系统中的费米面重构和Lifshitz拓扑跃迁的机制和后果，以及它们与化学成分或磁场或压力变化下的不稳定性的关系，获得定量的了解;（ii）准确预测具有重大技术重要性的特定基准材料的性能，其表现出与费米面变化相关的有趣行为，并且是当前实验的焦点，例如，三烯酸锶、铱酸锶和费米子超导体。(iii)对这些材料的实验提出具体的建议，以测试新的理论，（iv）最终实现对这些相关材料的性能的可靠控制。这是与技术发展直接相关的基础研究，因为我们选择的基准材料涵盖了广泛的潜在应用。超导SrRu 2 O 4有望具有马约拉纳束缚态，使其成为实现拓扑量子计算机量子比特的候选者。铱酸锶的特点是自旋轨道耦合和莫特物理之间的微妙相互作用，这可以导致新一代的自旋电子器件，而在压力下控制超导体的性能，将为超导工业开辟新的途径。