CAREER: Weak and Strong Correlations in Topological Semimetals

职业：拓扑半金属的弱相关性和强相关性

• 批准号: 2047193
• 负责人: Pavan Hosur
• 金额: $ 57.5万
• 依托单位: University of Houston
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-15 至 2026-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2047193&HistoricalAwards=false
• 关键词: CAREER; Weak; Strong; Correlations; Topological

NON-TECHNICAL SUMMARYThis CAREER award supports theoretical and computational research, and education on topological semimetals and the way electrons organize themselves in these materials. Most solids can be thought of as being either insulators or conductors - often metals. A closer examination, however, reveals rich sub-categories including semiconductors such as silicon, that are insulators at the absolute zero of temperature but show substantial conduction at room temperature, and semimetals such as bismuth, that are formally metals at zero temperature but at higher temperatures have several orders-of-magnitude lower conductivities than metals like copper.Over the past decade, the influx of ideas from mathematics in the area of topology into solid-state physics has spawned a new family of semimetals, namely, topological semimetals, of which graphene and Weyl semimetals are the most famous examples. These materials are "true" semimetals, in the sense that their properties at all temperatures are intermediate between those of metals and of insulators. Topological semimetals are fascinating materials: on one hand, they enable access to the physics related to the fundamental particles that make up matter through table-top experiments, while on the other hand, they tend to have conduction properties which make them attractive platforms for electronic device technologies.In this project, the PI and his team will theoretically investigate various fundamental aspects of topological semimetals, such as the tendency of electrons confined to their surfaces to organize themselves in states in which the electrons are ordered in some way, like magnetism or the cooperative state of superconductivity in which electrons move without any resistance. The range of the investigation reaches to electronic properties related to how electrons move in single atomic layer and two-layer structures of graphene. These aspects of graphene are challenging to study using existing techniques because standard analytical theoretical descriptions begin to break down while computational approaches are too limited or become prohibitively costly. Thus, the team of researchers will develop a new numerical algorithm tailored for investigating physics in this regime.The team will integrate the above research with concerted activities that harness technology for surmounting hurdles in education and outreach in the post-COVID era. Specifically, they will design mobile games that teach undergraduate physics content, build an "analogy inventory" to improve communication between physics and other STEM fields, organize a virtual conference on topological semimetals and develop innovative pedagogical strategies suitable for online and social distancing-compliant classrooms.TECHNICAL SUMMARYThis CAREER award supports theoretical and computational research, and education on topological semimetals. Topological semimetals (TSMs) are a cornerstone of topological condensed matter and, thanks to their gapless spectrum, present unique challenges and opportunities compared to their gapped counterparts such as topological insulators. The PI will explore, craft innovative tools for and tackle pressing theoretical issues in TSMs to unearth exotic phenomena in both weakly and strongly correlated regimes. This CAREER project is organized in 4 thrusts. Thrust 1 is focused on three-dimensional TSMs, adopting a clever surface-centric approach to reveal qualitatively new weak-correlation physics rooted in the interpolating-dimensional nature of the surface states and their inseparability from the bulk. This includes the quantum effects of weak disorder, spontaneous magnetization, and superconductivity, and also includes robust Majorana wires in mixed real-and-momentum space. Thrust 2 develops the primary tool for Thrust 3, namely, an innovative algorithm that is tailored for probing finite temperature properties of generic, non-integrable systems using the eigenstate thermalization hypothesis. Thrust 3 focuses on the strongly correlated regime of graphene-based systems. In particular, it inspects the microscopic processes that drive hydrodynamic transport in graphene and the finite temperature phases, including possible pseudogap and strange metal phases, in twisted bilayer graphene. Thrust 4 complements the research through concerted activities for surmounting hurdles in education and outreach in the post-COVID era using technology. Specifically, the PI and his team will design mobile games that teach undergraduate physics content, build an “analogy inventory” to improve communication between physics and other STEM fields, organize a virtual conference on TSM-research and develop innovative teaching strategies suitable for online and social distancing-compliant classrooms.This project is aimed to transform our collective understanding of TSMs by tackling fundamental issues in the field that arise from rapid experimental progress. For instance, Thrust 1 will clarify puzzles in magneto-transport experiments on TSMs, determine whether weak disorder can localize the surface states, provide theoretical support to surface superconductivity seen in TSMs and unveil scenarios where the surface spontaneously orders before the bulk does even though the latter has a higher dimensionality. It will also reveal a new class of non-local Majorana fermions and examine their potential for storing quantum information. The algorithm developed in Thrust 2 is a new approach to strongly correlated systems that could be useful for studying finite temperature equilibrium physics in unsolved regimes plagued by the Monte-Carlo sign-problem such as frustrated spin models and fermionic systems lacking quasiparticles. It transforms the eigenstate thermalization hypothesis from a useful qualitative conjecture to the basis for practical calculation. Thrust 3 will help dissect transport data in experimental graphene samples, which are increasingly approaching the quality needed for the electrons to exhibit hydrodynamic transport. It will also help map out the potentially rich and largely unexplored finite temperature phase diagram of twisted bilayer graphene.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.

该职业奖支持理论和计算研究，以及拓扑半金属和电子在这些材料中的组织方式的教育。大多数固体可以被认为是绝缘体或导体——通常是金属。然而，更仔细的研究揭示了丰富的子类别，包括半导体，如硅，在绝对零度温度下是绝缘体，但在室温下表现出实质性的导电性，以及半金属，如铋，在零温度下是正式的金属，但在更高的温度下，其导电性比铜等金属低几个数量级。在过去的十年中，拓扑学领域的数学思想涌入固态物理领域，催生了一个新的半金属家族，即拓扑半金属，其中石墨烯和Weyl半金属是最著名的例子。这些材料是“真正的”半金属，因为它们在任何温度下的性能都介于金属和绝缘体之间。拓扑半金属是令人着迷的材料：一方面，它们可以通过桌面实验获得与构成物质的基本粒子相关的物理学，而另一方面，它们往往具有导电特性，这使它们成为电子设备技术的有吸引力的平台。在这个项目中，PI和他的团队将从理论上研究拓扑半金属的各种基本方面，比如电子被限制在其表面的趋势，在电子以某种方式有序的状态下组织自己，比如磁性或超导的合作状态，电子在这种状态下没有任何阻力地移动。研究的范围涉及到与电子如何在石墨烯的单原子层和双层结构中移动有关的电子特性。使用现有技术研究石墨烯的这些方面是具有挑战性的，因为标准的分析理论描述开始崩溃，而计算方法过于有限或变得过于昂贵。因此，研究小组将开发一种新的数值算法，专门用于研究这种情况下的物理学。该团队将把上述研究与协调一致的活动结合起来，利用技术克服后covid时代教育和外联方面的障碍。具体来说，他们将设计教授本科物理内容的手机游戏，建立“类比清单”以改善物理与其他STEM领域之间的交流，组织拓扑半金属的虚拟会议，并制定适合在线和符合社交距离的教室的创新教学策略。该职业奖支持理论和计算研究，以及拓扑半金属的教育。拓扑半金属（tsm）是拓扑凝聚态的基石，由于其无间隙的光谱，与拓扑绝缘体等有间隙的对应物相比，呈现出独特的挑战和机遇。PI将探索、制作创新工具并解决tsm中紧迫的理论问题，以发现弱相关和强相关体系中的奇异现象。这个CAREER项目分为4个部分。推力1专注于三维tsm，采用一种巧妙的表面中心方法来揭示定性的新弱相关物理，这些物理植根于表面态的插值维性质及其与体的不可分离性。这包括弱无序、自发磁化和超导的量子效应，也包括实动量混合空间中的坚固马约拉纳线。Thrust 2开发了Thrust 3的主要工具，即一种创新算法，该算法专门用于使用特征态热化假设探测一般不可积系统的有限温度特性。推力3侧重于石墨烯基系统的强相关机制。特别地，它考察了驱动石墨烯和有限温度相（包括可能的假间隙和奇怪的金属相）在扭曲双层石墨烯中的流体动力学输运的微观过程。重点4通过协调一致的活动，利用技术克服后covid时代教育和外联方面的障碍，对研究进行补充。具体来说，PI和他的团队将设计教授本科物理内容的手机游戏，建立一个“类比清单”以改善物理与其他STEM领域之间的交流，组织一个关于tsm研究的虚拟会议，并制定适合在线和符合社交距离的课堂的创新教学策略。该项目旨在通过解决因快速实验进展而产生的该领域的基本问题，改变我们对tms的集体理解。例如，推力1将澄清在tsm上的磁输运实验中的难题，确定弱无序是否可以局部化表面状态，为tsm中看到的表面超导性提供理论支持，并揭示表面自发有序的场景，即使后者具有更高的维度。它还将揭示一类新的非局部马约拉纳费米子，并研究它们存储量子信息的潜力。在Thrust 2中开发的算法是一种研究强相关系统的新方法，可用于研究受蒙特卡罗符号问题困扰的未解状态下的有限温度平衡物理，如受挫自旋模型和缺乏准粒子的费米子系统。它将本征态热化假设从一个有用的定性猜想转化为实际计算的基础。推力3将有助于解析实验石墨烯样品中的输运数据，这些数据越来越接近电子表现出流体动力学输运所需的质量。它还将有助于绘制出扭曲双层石墨烯的潜在丰富和大部分未开发的有限温度相图。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Anomalous surface conductivity of Weyl semimetals

• DOI: 10.1103/physrevb.106.245410
• 发表时间: 2021-12
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: H. Pal;Osakpolor Eki Obakpolor;P. Hosur

Surface Luttinger arcs in Weyl semimetals

• DOI: 10.1103/physrevb.106.l081112
• 发表时间: 2021-08
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Osakpolor Eki Obakpolor;P. Hosur

Intrinsic surface superconducting instability in type-I Weyl semimetals

• DOI: 10.1103/physrevb.108.165144
• 发表时间: 2023-04
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Aymen Nomani;P. Hosur

Fermi Arc Criterion for Surface Majorana Modes in Superconducting Time-Reversal Symmetric Weyl Semimetals

• DOI: 10.1103/physrevlett.127.187002
• 发表时间: 2021-10-26
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Giwa, Rauf;Hosur, Pavan
• 通讯作者: Hosur, Pavan

Polynomial-time algorithm for studying physical observables in chaotic eigenstates

研究混沌本征态物理可观测量的多项式时间算法

• DOI: 10.1103/physrevb.103.195159
• 发表时间: 2021
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Hosur, Pavan