CAREER: Probing an Emergent New Class of Electronic Liquid Crystals Using Synchrotron X-rays: Superconductors and Beyond

职业：利用同步加速器 X 射线探测新兴的新型电子液晶：超导体及其他

• 批准号: 1454926
• 负责人: Ruihua He
• 金额: $ 54万
• 依托单位: Boston College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-05-01 至 2017-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1454926&HistoricalAwards=false
• 关键词: CAREER; Probing; Emergent; New; Class

Nontechnical Abstract:New materials, from semiconductors to plastics, have revolutionized our lives. Liquid crystals, for example, have transformed the way that we display and transmit information. However, these advances occurred only after we had developed an understanding of the properties of these materials, which share the properties of both liquid and solids, and the complex phases (arrangements of molecules) that they exhibit. Recently, the ideas that underlie our understanding of liquid crystals are being applied to understand the electronic properties of new materials such as high temperature superconductors. A more detailed understanding of the properties of these materials will allow them to be optimized for applications such as power transmission and energy storage. Under this CAREER award the PI and his students will apply a unique combination of advanced x-ray techniques to study systems such as high-temperature superconductors and charge density wave materials with an ultimate goal of establishing a new understanding of these unique phases of quantum matter. Integrated into the research is a plan for education and outreach centering around two key research components-advanced x-ray facilities and superconductors. The former is provided through K-12 mentoring, undergraduate and graduate training at x-ray facilities and Boston College, course development, and outreach presentations for minority faculty. An outreach plan focused on superconductors is planned that features both lectures and maglev demonstrations to be given to the general public through participation in two programs run by the MIT Museum, to the students of regional middle and high schools through school visits, and to their teachers through organizing small training workshops.Technical Abstract: A central theme of condensed matter physics is to discover and understand the emergence of novel phases of quantum matter. Research in the past decade has brought a number of such phases to the limelight, including electronic liquid crystal phases. These quantum phases were literally proposed in analogy to the liquid crystalline phases of classical fluids in terms of their similarities in the patterns of broken symmetry. Two classes of electronic liquid crystalline phases, the electron nematics and smectics, have been primarily focused on and attracted significant interest. Here, the research team seeks a further generalization of that fascinating analogy through the incorporation of the third known major liquid crystalline phase--the cholesterics that breaks long-range chiral symmetry. Initial indications for the possible existence of electron cholesterics in a transition-metal dichalcogenide and some high-Tc superconductors have recently been found experimentally, showing its potential of being as prevalent as its nematic and smectic counterparts in quantum matter. In order to look into this intriguing possibility, the principal investigator proposes a comprehensive experimental survey in this emerging frontier with the aid of a unique combination of synchrotron x-ray techniques. These techniques are element specific and can directly probe electronic states via different physics processes on different chirality-related physical quantities. Their joint force allows the existing candidate phases to be scrutinized to previously unattainable depth, and lays a foundation for future explorations on other condensed matter systems. Specifically, the proposed studies of cuprate superconductors aim for a unified understanding based on a unique chiral perspective of charge ordering phenomena - a current focus of the high-Tc field.

从半导体到塑料，新材料已经彻底改变了我们的生活。例如，液晶改变了我们显示和传输信息的方式。然而，这些进展只有在我们对这些材料的特性有了了解之后才会发生，这些材料具有液体和固体的特性，以及它们所表现出的复杂相（分子排列）。最近，我们理解液晶的基础思想正被应用于理解新材料的电子特性，如高温超导体。对这些材料特性的更详细的了解将使它们能够针对诸如电力传输和能量存储等应用进行优化。在这个职业奖下，PI和他的学生将应用先进的x射线技术的独特组合来研究系统，如高温超导体和电荷密度波材料，最终目标是建立对量子物质这些独特相的新理解。与研究相结合的是围绕两个关键研究组成部分——先进的x射线设备和超导体——的教育和推广计划。前者是通过K-12辅导、x射线设施和波士顿学院的本科生和研究生培训、课程开发以及为少数族裔教师提供的拓展演讲来提供的。一项以超导体为重点的推广计划将以讲座和磁悬浮演示为特色，通过麻省理工学院博物馆举办的两个项目向公众提供，通过学校参观向地区初中和高中的学生提供，并通过组织小型培训讲习班向他们的老师提供。技术摘要：凝聚态物理的中心主题是发现和理解量子物质新相的出现。在过去十年的研究中，许多这样的相位引起了人们的注意，其中包括电子液晶相位。这些量子相实际上是类比于经典流体的液晶相，因为它们在对称性破缺模式上具有相似性。两类电子液晶相，即电子向列线相和微晶相，已经引起了人们的关注和极大的兴趣。在这里，研究小组通过结合第三种已知的主要液晶相——破坏远程手性对称的胆固醇，寻求对这个迷人的类比的进一步推广。最近在实验中发现了过渡金属二硫化物和一些高tc超导体中可能存在电子胆固醇的初步迹象，表明其在量子物质中与向列和近晶对应物一样普遍存在的潜力。为了研究这一有趣的可能性，首席研究员建议在这一新兴领域进行全面的实验调查，借助同步加速器x射线技术的独特组合。这些技术是特定于元素的，可以通过不同的物理过程在不同的手性相关物理量上直接探测电子状态。他们的联合力量使现有的候选相能够被仔细检查到以前无法达到的深度，并为未来探索其他凝聚态系统奠定了基础。具体而言，铜超导体的研究旨在基于独特的手性视角对电荷有序现象进行统一的理解-这是当前高tc领域的焦点。