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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710531
• 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.

最近，在理解弱相互作用电子系统中所谓的物质拓扑相方面取得了巨大进展。在这里，拓扑学起着重要的作用，因为物质的这些相在材料参数的光滑变形下具有一定的物理量不变的特征。因此，这种相的许多物理性质天生对材料的各种微观细节不敏感。拓扑相的最初想法最近获得了2016年的诺贝尔物理学奖。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。这些金属表面状态对杂质等缺陷具有内在的弹性。这种所谓的表面状态拓扑保护被认为是一种有前途的新技术。