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Quantum Dynamics in Correlated Spin Systems

基本信息

批准号：
EP/S016465/1
负责人：
Sean Richard Giblin
金额：
$ 62.19万
依托单位：
CARDIFF UNIVERSITY
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FS016465%2F1
关键词：
Quantum Dynamics Correlated Spin Systems

项目摘要

Contrary to our natural perceptions materials and devices which rely on quantum properties play an integral role in our everyday life. Even seemingly mundane phenomena such as electrical conduction relies on the band gap picture which is fundamentally quantum mechanical in nature; indeed a theoretical model which describes why, for example, copper is a metal, and silicon a semiconductor can be constructed using the quantum mechanics of electrons interacting with the crystal lattice upon which they sit. Extensions of this picture have led to the explanation of some superconductors, materials which conduct electricity without any resistance. Superconductors, although initially of fundamental interest at the time of their discovery in 1911, have more recently underpinned the function of MRI scanners in hospitals. Although the timelines from discovery, fundamental experimentation and interest to commercial applications are long, this has generally been the pathway to paradigm shifting technologies for society.This methodology of investigating fundamental properties of matter remain highly relevant and indeed, quantum topological materials are of general interest today. Most devices are fabricated in the micro-metre regime, but a full understanding of the parent bulk material is generally required to design and control the materials used. This proposal is firmly based in the realm of frontier science, and will exploit new techniques that have been developed by the investigation team to tune and understand quantum interactions at a fundamental level. The project is based upon a material known as spin ice. The beauty of this material is that previous research has identified the basic, apparently classical, properties that are well-understood. We want to go further to investigate and characterise emergent states, where properties can be manipulated by changing experimental variables and the effect of hitherto neglected quantum dynamics that underly the observed physical behaviour. This proposal exploits our existing knowledge of the classical properties of spin ice and will investigate underlying quantum processes. In particular we will study the quantum tunneling of spin ice's so-called magnetic monopoles. This will allow us to understand how to tune quantum states in the future. In correlated spin physics a clear goal has been to understand the crossover between classical and quantum behaviour. In this proposal we will investigate spin ice which has a very large magnetic moment and has often been described as a classical magnet, to reveal underlying quantum behaviour. We have identified several methods to explore this, and importantly all require our unique high frequency susceptometer that we have developed over the past few years. We have already identified dilute spin ice as a material to investigate tunneling of the magnetisation and propose to investigate the phase diagram as a function of magnetic field. This will allow us to understand how magnetic monopoles hop at low temperatures in this material, and how the emergent and non-equilibrium states develop. Moreover we can tune a magnetic field applied to spin ice to look at a critical point where quantum fluctuations may play a significant role. We can also look at the tunneling of monopoles in new spin ice materials at higher frequency than previously possible. This grant will allow us to develop and retain high-level technical and scientific expertise and train a future scientific leader in developing cutting-edge science and technology.

与我们的自然认知相反，依赖于量子特性的材料和设备在我们的日常生活中扮演着不可或缺的角色。甚至像导电这样看似平凡的现象也依赖于本质上是量子力学的带隙图像;事实上，一个理论模型描述了为什么，例如，铜是金属，硅是半导体，可以使用电子与它们所在的晶格相互作用的量子力学来构建。这一图景的延伸导致了对某些超导体的解释，这些超导体是一种无电阻导电的材料。超导体虽然在1911年被发现时就引起了人们的根本兴趣，但最近已经成为医院MRI扫描仪的基础。虽然从发现、基础实验和兴趣到商业应用的时间线很长，但这通常是社会范式转变技术的途径。这种研究物质基本性质的方法仍然高度相关，事实上，量子拓扑材料今天受到普遍关注。大多数器件都是在微米范围内制造的，但通常需要对母体散装材料有充分的了解才能设计和控制所使用的材料。该提案牢固地建立在前沿科学领域，并将利用调查小组开发的新技术来调整和理解基本水平的量子相互作用。该项目是基于一种被称为自旋冰的材料。这种材料的美妙之处在于，以前的研究已经确定了基本的，显然是经典的，被充分理解的性质。我们希望进一步研究和发现涌现态，在这些状态中，可以通过改变实验变量和迄今为止被忽视的量子动力学效应来操纵性质，而量子动力学是所观察到的物理行为的基础。这个提议利用了我们现有的自旋冰的经典性质的知识，并将调查潜在的量子过程。特别是我们将研究自旋冰的所谓磁单极子的量子隧穿。这将使我们能够理解如何在未来调整量子态。在相关自旋物理学中，一个明确的目标是理解经典和量子行为之间的交叉。在这个提议中，我们将研究自旋冰，它有一个非常大的磁矩，并经常被描述为一个经典的磁铁，揭示潜在的量子行为。我们已经确定了几种方法来探索这一点，重要的是，所有这些方法都需要我们在过去几年中开发的独特的高频电磁辐射计。我们已经确定了稀自旋冰作为一种材料来研究磁化的隧穿，并建议研究作为磁场函数的相图。这将使我们能够理解磁单极子如何在这种材料中的低温下跳跃，以及新兴和非平衡状态如何发展。此外，我们可以调整施加在自旋冰上的磁场，以观察量子涨落可能起重要作用的临界点。我们还可以在比以前更高的频率下观察新的自旋冰材料中单极子的隧穿。这笔赠款将使我们能够发展和保留高水平的技术和科学专业知识，并培养未来的科学领导者，发展尖端科学和技术。