Muon Studies of Quantum Materials and Novel States of Matter

量子材料和新物态的 μ 子研究

• 批准号: RGPIN-2016-04508
• 负责人: Sonier, Jeffrey
• 金额: $ 2.91万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=665619
• 关键词: Muon; Studies; Quantum; Materials; Novel

Quantum materials comprise a wide range of scientifically fascinating and technologically important phenomena, including high-temperature superconductivity, non-Fermi liquid behaviour, colossal magnetoresistance, and countless forms of magnetism and ferroelectricity. These unusual behaviours seemingly arise from quantum fluctuations extending beyond a phase transition that has been driven to absolute zero temperature (T = 0) by a non-thermal control parameter (applied pressure, applied magnetic field or chemical manipulation of electron density). Understanding so-called quantum phase transitions (QPTs) and the accompanying emergent quantum phenomena is a grand challenge and a central thrust of modern condensed matter physics.***QPTs and associated critical behaviour can be severely modified by disorder. Disorder may be inherent, intentionally introduced by changing the chemical composition, or intrinsically driven by a close competition between different ground states. In general, disorder-induced QPTs are predicted to drive correlated-electron systems to novel quantum disordered phases with rather exotic properties.***The investigation of the effects of disorder on quantum critical phenomena necessitates local-probe experimental techniques that are capable of recognizing and characterizing disorder or phase separation in the quantum critical region. The muon spin rotation/relaxation (μSR) technique is well suited in this regard to provide insight on QPTs not attainable by other methods. When implanted in a material, the positive muon (μ+) serves as a local probe of internal magnetic field, allowing measurements of magnetic and superconducting properties. Moreover, μSR has a unique sensitivity to volume fractions of magnetic regions. ***I plan to concentrate my research on μSR investigations of quantum materials to provide a local probe's perspective on non-thermal controlled quantum criticality. My approach will be to exploit new μSR experimental capabilities in Canada, utilize facilities abroad and forge new research partnerships to gain fundamental insight on quantum critical phenomena in a variety of strongly-correlated electron systems (e.g., topological insulators, unconventional superconductors, novel magnetically-frustrated metals).***The proposed research initiatives aim to determine the extent to which phase separation is a ubiquitous phenomenon of magnetic QPTs and to elucidate novel states of matter. The knowledge gained will support quantum materials research and technology, which is a current strategic priority research area in Canada. My research plan provides a fertile HQP training ground for enhancing the workforce skills of trainees through exposure to state-of-the-art technologies, engagement in cutting-edge science, extensive collaborations, and opportunities to travel and disseminate research results.

量子材料包括广泛的科学上令人着迷和技术上重要的现象，包括高温超导、非费米液体行为、巨磁电阻以及无数形式的磁性和铁电。这些不同寻常的行为似乎是由于量子涨落延伸到相变之外，而相变是由非热控制参数(外加压力、外加磁场或电子密度的化学操纵)驱动到绝对零度(T=0)的。理解所谓的量子相变(QPT)和伴随出现的量子现象是一个巨大的挑战，也是现代凝聚态物理学的中心任务。*QPT和相关的临界行为可以被无序严重改变。无序可能是内在的，可能是通过改变化学成分而故意引入的，也可能是由不同基态之间的激烈竞争内在驱动的。一般来说，无序诱导的QPTs被预测为驱动相关电子系统形成具有相当奇异性质的新型量子无序相。*研究无序对量子临界现象的影响需要能够识别和表征量子临界区无序或相分离的局域探针实验技术。在这方面，介子自旋旋转/弛豫(μSR)技术非常适合于提供其他方法所不能获得的对QPT的洞察。当正Muon(μ+)被植入材料中时，它充当内部磁场的局部探测器，从而能够测量磁性和超导性质。此外，μSR对磁区的体积分数具有独特的敏感性。*我计划将我的研究集中在量子材料的μSR调查上，以提供一个本地探测器对非热控制量子临界性的观点。我的方法将是利用加拿大新的μSR实验能力，利用国外的设施并建立新的研究伙伴关系，以获得对各种强关联电子系统(例如，拓扑绝缘体、非传统超导体、新型磁阻金属)中量子临界现象的基本见解。*拟议的研究计划旨在确定相分离在多大程度上是磁性QPT的普遍现象，并阐明物质的新状态。所获得的知识将支持量子材料研究和技术，这是加拿大目前的战略优先研究领域。我的研究计划提供了肥沃的HQP培训基础，通过接触最先进的技术、参与尖端科学、广泛的合作以及旅行和传播研究成果的机会来提高学员的劳动力技能。