Strange metals and the phases of quantum materials

奇异金属和量子材料的相

• 批准号: 2245246
• 负责人: Subir Sachdev
• 金额: $ 66万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2027-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2245246&HistoricalAwards=false
• 关键词: Strange; metals; phases; quantum; materials

NONTECHNICAL SUMMARYThis award supports theoretical research which will examine the so-called "strange metal" phase of quantum matter, which is ubiquitous in systems in which the electron-electron interaction is very strong. Quantum mechanics was initially developed in the early twentieth century as a theory of the motion of a single electron around the nucleus of a hydrogen atom, but it can also describe the motion of a large number of electrons in metals and semiconductors, and this description was vital to the electronics revolution. The past few decades have witnessed the discovery of numerous "quantum materials" in which the role of quantum mechanics is more profound than previously thought and not well understood. In quantum materials, it is important to treat the motion of electrons collectively, and account for the entanglement between the different electrons. Most prominent among these new materials are the high temperature superconductors found in a series of compounds which contain copper, oxygen, and numerous other transition metals, which can conduct electricity without any loss of energy above a relatively high temperature. In this project, the PI and his team will develop a theory of electronic motion in such materials focusing especially on a regime of temperatures and electron density where the motion of electrons is most unlike those in conventional materials. This regime is often called the "strange metal" phase, and it is clear that the mutual entanglement of electrons plays an important role in bringing out the peculiar properties of this phase. This project will build on the successes of a model previously developed by the PI, which provides a simple setting in which the entanglement between the electrons is, in a sense, maximal, and yet the equations of quantum mechanics can be solved exactly. The PI and his collaborators have recently extended this model to a more realistic setting which maintains its solvability, and this yields an encouraging correspondence with observations on strange metals. This project will extend this understanding of the strange metal to other phases of quantum materials, including those exhibiting superconductivity at high temperatures and microstructures that consist of one-atom-thick sheets of carbon atoms stacked in various configurations on top of each other.This award will also contribute to the development of the scientific workforce by supporting the training of graduate students and postdoctoral associates in topics at the forefront of theoretical condensed matter physics. Furthermore, the PI will continue to pursue an active program of public lectures, interviews, colloquia, and lectures at schools for advanced graduate students.TECHNICAL SUMMARYThis award supports theoretical research which will examine the "strange metal" phase of quantum matter, which is ubiquitous in correlated electron systems, especially those that exhibit higher temperature superconductivity. A complete, quantitative understanding of the strange metal phase is essential to progress in the theory of quantum materials. The PI and his team have recently made progress on a theory of strange metals, which has the attractive features of being simple, universal, and broadly applicable across the range of correlated materials. In this project, the team will further develop the Sachdev-Ye-Kitaev model and related theories and compare the results quantitatively with numerous experimental probes. For the cuprate superconductors, the strange metal phase will be related to various neighboring phases, including the pseudogap, the superconductor, and the charge-ordered phases. Another focus area of this project is on graphene microstructures and will include studies of nanoscale graphene flakes and the manner in which they can exhibit signatures of the non-Fermi liquid of the Sachdev-Ye-Kitaev model. This award will also contribute to the development of the scientific workforce by supporting the training of graduate students and postdoctoral associates in topics at the forefront of theoretical condensed matter physics. Furthermore, the PI will continue to pursue an active program of public lectures, interviews, colloquia, and lectures at schools for advanced graduate students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术摘要该奖项支持理论研究，该研究将检查量子物质的所谓“奇怪金属”相，这种相在电子-电子相互作用非常强的系统中普遍存在。量子力学最初是在二十世纪初期发展起来的，作为单个电子绕氢原子核运动的理论，但它也可以描述金属和半导体中大量电子的运动，而这种描述是对电子革命至关重要。在过去的几十年里，人们发现了大量的“量子材料”，其中量子力学的作用比以前想象的更加深刻，但人们并没有很好地理解。在量子材料中，重要的是集中处理电子的运动，并解释不同电子之间的纠缠。这些新材料中最突出的是在一系列含有铜、氧和许多其他过渡金属的化合物中发现的高温超导体，它们可以在相对较高的温度以上导电而不会损失任何能量。在这个项目中，首席研究员和他的团队将开发此类材料中的电子运动理论，特别关注温度和电子密度的范围，其中电子的运动与传统材料中的运动最不同。这种状态通常被称为“奇怪的金属”相，很明显，电子的相互纠缠在展现该相的特殊性质方面发挥着重要作用。该项目将建立在 PI 先前开发的模型的成功基础上，该模型提供了一个简单的设置，其中电子之间的纠缠在某种意义上是最大的，但可以精确求解量子力学方程。 PI 和他的合作者最近将该模型扩展到更现实的环境，保持其可解性，这与对奇怪金属的观察产生了令人鼓舞的对应关系。该项目将对这种奇怪金属的理解扩展到量子材料的其他相，包括那些在高温下表现出超导性的材料以及由单原子厚的碳原子片组成的微观结构，这些碳原子片以各种配置相互堆叠。还将通过支持理论凝聚态物理前沿主题的研究生和博士后培训，为科学队伍的发展做出贡献。此外，PI 将继续开展一项积极的计划，包括公开讲座、访谈、座谈会以及在学校为高级研究生举办的讲座。技术摘要该奖项支持理论研究，该研究将研究普遍存在的量子物质的“奇怪金属”相。在相关电子系统中，尤其是那些表现出更高温度超导性的系统中。对奇异金属相的完整、定量理解对于量子材料理论的进步至关重要。 PI和他的团队最近在奇异金属理论方面取得了进展，该理论具有简单、通用且广泛适用于相关材料范围的吸引人的特点。在这个项目中，团队将进一步发展Sachdev-Ye-Kitaev模型和相关理论，并将结果与​​大量实验探针进行定量比较。对于铜酸盐超导体，奇异金属相将与各种相邻相相关，包括赝能隙、超导体和电荷有序相。该项目的另一个重点领域是石墨烯微观结构，并将包括纳米级石墨烯薄片及其表现出 Sachdev-Ye-Kitaev 模型的非费米液体特征的方式的研究。该奖项还将通过支持研究生和博士后研究员在理论凝聚态物理前沿主题的培训，为科学队伍的发展做出贡献。此外，PI 将继续开展一项积极的计划，包括在学校为高级研究生举办公开讲座、访谈、座谈会和讲座。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优势和更广泛的评估进行评估，认为值得支持。影响审查标准。