Superconductivity and Other Quantum Orderings in the Lighter Elements

轻元素中的超导性和其他量子有序性

• 批准号: 0907425
• 负责人: Neil Ashcroft
• 金额: $ 37.9万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0907425&HistoricalAwards=false
• 关键词: Superconductivity; Other; Quantum; Orderings; Lighter

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). TECHNICAL SUMMARY: This award supports theoretical research and education focused mainly on the light elements, including hydrogen under conditions of high pressure and high temperature. The PI aims to elucidate quantum orderings, both in hydrogen and in hydrogen alloyed with other light element systems. Of increasing prominence in these systems is the enduringly fundamental and pragmatic area of superconductivity, impelled by the recent and quite dramatic discovery of superconductivity occurring in the metallic state of silane. That this could be a possibility was already raised in research supported by the previous grant and companion predictions that the hitherto 'simple' elements would adopt structures of considerable complexity at similar conditions were also swiftly borne out by experiment. It is remarkable that many of the elements hitherto regarded as 'simple' are observed to take up structures at higher densities even exhibiting incommensurabilities. A major theme of the research is spurred by striking recent advances in experimental high pressure physics. The PI aims to elucidate the physics of the superconducting state, and particularly the role of electronic fluctuation in multi-band and quasi-localized contexts. High temperature superconductivity has long been predicted to occur in metallic phases of hydrogen and now more recently in hydrogen dominant metallic alloys. Further development of the theory for this class of system seems in order, especially to explore the possibility of further orderings that might accompany sublattice melting. For pure hydrogen itself, co-existence of superfluidity and superconductivity has been predicted for liquid metallic (near) ground states, and extension of the theory now to the mixed symmetry system embodied by liquid metallic deuterium is an interesting avenue to pursue, again with an eye towards experimental realization. In electronic terms all of these systems are highly inhomogeneous, as guaranteed by the cusp theorem, and this work will continue the development of weighted density and related approaches to the density functional viewpoint of the associated electronic structures, and could help illuminate the physics of transitions from the metallic state back to insulating or semiconducting.NON-TECHNICAL SUMMARY: This award supports theoretical research and education in condensed matter physics focused mainly on the light elements, including hydrogen under extremes of pressure and temperature. A key feature of this work is the prediction of key signatures that could be observed in experiments. While hydrogen under enormous pressure exists in various places in our solar system and elsewhere in the universe, recent advances in experimental high pressure techniques suggest that the discovery of exciting new phases of matter with potential technological applications is coming within grasp. Among the possibilities are superconducting states that occur at high temperature in the light elements under high pressure. The PI will continue and extend his theoretical work to predict and explore new states of matter that may emerge in the seemingly simplest elements. Hydrogen and hydrogen-dominant metallic alloys under high pressure will be a particular focus of the work. This research may have impact on other disciplines and will provide a training ground for future scientists.

该奖项根据 2009 年美国复苏和再投资法案（公法 111-5）提供资金。技术摘要：该奖项支持主要针对轻元素（包括高压高温条件下的氢）的理论研究和教育。该 PI 旨在阐明氢以及氢与其他轻元素系统的合金中的量子有序性。在这些系统中日益突出的是超导性的持久基础和实用领域，这是受到最近在硅烷金属态中发生的超导性的相当引人注目的发现的推动。这可能是一种可能性，在之前的资助支持的研究中已经提出，并且伴随的预测是迄今为止“简单”的元素将在类似的条件下采用相当复杂的结构，这也很快得到了实验的证实。值得注意的是，许多迄今为止被认为是“简单”的元素被观察到以更高的密度占据结构，甚至表现出不可通约性。这项研究的一个主要主题是受到实验高压物理学的最新进展的推动。该 PI 旨在阐明超导态的物理原理，特别是电子涨落在多带和准局域环境中的作用。长期以来，人们一直预测高温超导性会出现在氢的金属相中，最近又出现在以氢为主的金属合金中。此类系统理论的进一步发展似乎是有必要的，特别是探索可能伴随亚晶格熔化的进一步排序的可能性。对于纯氢本身来说，液态金属（近）基态超流性和超导性的共存已被预测，并且现在将理论扩展到液态金属氘所体现的混合对称系统是一个有趣的追求途径，同样着眼于实验实现。从电子术语来看，正如尖点定理所保证的那样，所有这些系统都是高度不均匀的，这项工作将继续开发加权密度和相关电子结构的密度泛函观点的相关方法，并且可以帮助阐明从金​​属态回到绝缘态或半导体态的转变物理学。非技术摘要：该奖项支持凝聚态物理的理论研究和教育 主要关注轻元素，包括极端压力和温度下的氢。 这项工作的一个关键特征是预测可以在实验中观察到的调号。虽然巨大压力下的氢存在于太阳系和宇宙其他地方的不同地方，但实验高压技术的最新进展表明，发现具有潜在技术应用的令人兴奋的新物质相已指日可待。其中一种可能性是轻元素在高压下在高温下出现超导态。 PI 将继续并扩展他的理论工作，以预测和探索看似最简单的元素中可能出现的新物质状态。高压下的氢和以氢为主的金属合金将是该工作的特别重点。这项研究可能会对其他学科产生影响，并将为未来的科学家提供训练场。