Topology and Correlation in Quantum Materials

量子材料中的拓扑和相关性

• 批准号: RGPIN-2017-03774
• 负责人: Kim, YongBaek
• 金额: $ 4.08万
• 依托单位: University of Toronto
• 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=655591
• 关键词: Topology; Correlation; Quantum; Materials

Recently, there has been tremendous progress in understanding so--called topological phases of matter in weakly interacting electron systems. Here topology plays an important role in the sense that these phases of matter are characterized by certain physical quantities invariant under smooth deformations of material parameters. As a result, many physical properties of such phases are inherently insensitive to various microscopic details of materials. The initial idea of topological phases has recently been awarded the Physics Nobel prize in 2016. The most studied example of topological phases is topological insulators, where the bulk of the material is electrically inert, but the surface is metallic. These metallic surface states are intrinsically resilient to imperfections such as impurities. This so--called topological protection of surface states is considered a promising route to new technologies. ******On the other hand, topological materials in strongly interacting electron systems are relatively less explored. It has become clear that our current understanding of weakly interacting electron systems cannot directly be applied to systems with strong correlation. In the current proposal, the principal investigator (PI) proposes to explore possible topological phases in strongly correlated quantum materials, where the electron interactions play a fundamentally important role. In particular, the PI aims to make direct connection between theoretical models for these novel phases and real materials. The virtue of finding such phases is that they would allow robust and peculiar electronic/magnetic properties in the bulk and surface, which are not possible in weakly interacting analogs. Further, strong electron interaction would provide additional knobs to control topologically protected surface states, for example via magnetism, and offer more flexible applications to new technologies.******Recently, the PI's group has pioneered new directions in this line of research and developed several theoretical models for correlated quantum materials, where strong entanglement between spin and orbital degrees of freedom of electrons plays a pivotal role. Building on these achievements, the PI is planning to investigate general organizing principles for correlated topological phases. This would open a new avenue in understanding of new topological phenomena, unique to correlated electron materials. Utilizing unusual surface states of topological materials, the PI would also explore engineered interface states between topological and conventional systems. These exercises would offer great intellectual challenges to both theories and experiments, and significant societal impact via future technological applications such as fundamentally new ways to perform certain computational tasks in next generation computers.

近年来，人们对弱相互作用电子系统中物质的拓扑相的理解有了很大的进展。在这里拓扑起着重要的作用，在这个意义上说，这些阶段的物质的特点是某些物理量不变的平滑变形下的材料参数。因此，这些相的许多物理性质本质上对材料的各种微观细节不敏感。拓扑相的最初想法最近被授予2016年诺贝尔物理学奖。拓扑相研究最多的例子是拓扑绝缘体，其中大部分材料是电惰性的，但表面是金属的。这些金属表面状态本质上对诸如杂质的缺陷具有弹性。这种所谓的表面状态的拓扑保护被认为是新技术的一条有前途的路线。* 另一方面，强相互作用电子系统中的拓扑材料相对较少探索。很明显，我们目前对弱相互作用电子系统的理解不能直接应用于强关联系统。在目前的提案中，首席研究员（PI）建议探索强相关量子材料中可能的拓扑相，其中电子相互作用起着至关重要的作用。特别是，PI旨在将这些新相的理论模型与真实的材料直接联系起来。发现这样的相的优点是，它们将允许在体和表面中具有鲁棒和特殊的电子/磁性，这在弱相互作用的类似物中是不可能的。此外，强电子相互作用将提供额外的旋钮来控制拓扑保护的表面状态，例如通过磁性，并为新技术提供更灵活的应用。最近，PI的团队在这一研究领域开创了新的方向，并为相关量子材料开发了几种理论模型，其中电子的自旋和轨道自由度之间的强纠缠起着关键作用。在这些成就的基础上，PI计划研究相关拓扑相的一般组织原则。这将为理解新的拓扑现象开辟一条新的途径，这是相关电子材料所独有的。利用拓扑材料的不寻常表面状态，PI还将探索拓扑和传统系统之间的工程界面状态。这些练习将为理论和实验提供巨大的智力挑战，并通过未来的技术应用（例如在下一代计算机中执行某些计算任务的全新方法）产生重大的社会影响。