Topological quantum phase transitions in high-temperature superconductors

高温超导体中的拓扑量子相变

• 批准号: 345197117
• 负责人: Professor Dr. Mathias Scheurer
• 金额: --
• 依托单位: Department of Physics
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 无数据
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/345197117?language=en
• 关键词: Topological; quantum; phase; transitions; temperature

One of the most fundamental aspects of condensed matter physics is the classification of different phases of matter. A systematic approach is given by Landau's theory of phase transitions according to which different phases are characterized by distinct symmetry properties. This allows describing many thermal transitions (such as the liquid-solid transition) as well as quantum phase transitions, i.e., phase transitions at zero temperature. Instead of exhibiting different symmetries, phases can also be distinguished by their topology, i.e., global properties such as the degeneracy of the ground state, which is, e.g., important for the quantum Hall effects.Many experimental observations indicate that topological quantum phase transitions are also central to the phase diagram of the copper-based high-temperature superconductors. These materials are of high interest, not only because of the defining high transition temperature and the associated technological potential but also due to the complex phase diagram that, in many regards, still lacks theoretical understanding.In this project, we will use the recent progress in developing realistic theoretical models which exhibit the topological phases that are relevant for the copper-based high-temperature superconductors in order to improve our microscopic understanding of these materials. In particular, the predictions of different models for transport properties in the normal state, the sensitivity of the different phases to disorder, the different superconducting instabilities as well as for resonance modes in neutron scattering and Raman response will be analyzed with controlled theoretical approaches and compared in detail with experimental observations. The long-term objective is to establish a minimal and realistic low-energy model that agrees with a large number of different experiments. Important consequences for other classes of high-temperature superconductors and further strongly correlated materials with similar phenomenological properties are expected.

凝聚态物理学最基本的方面之一是物质不同相的分类。朗道的相变理论给出了一个系统的方法，根据该理论，不同的相位具有不同的对称性。这允许描述许多热转变（例如液-固转变）以及量子相变，即，零温度下的相变。相也可以通过它们的拓扑来区分，而不是表现出不同的对称性，即，全局性质，例如基态的简并性，例如，许多实验观测表明拓扑量子相变也是铜基高温超导体相图的中心。这些材料非常令人感兴趣，不仅是因为其定义的高转变温度和相关的技术潜力，还因为其复杂的相图在许多方面仍然缺乏理论理解。在该项目中，我们将利用最近的进展，在发展现实的理论模型，表现出拓扑相，是相关的铜基高，温度超导体，以提高我们对这些材料的微观理解。特别是，在正常状态下的传输特性的不同模型的预测，不同阶段的无序的敏感性，不同的超导不稳定性，以及在中子散射和拉曼响应的共振模式将与控制的理论方法进行分析，并与实验观测进行详细比较。长期目标是建立一个最小的和现实的低能量模型，同意大量不同的实验。其他类别的高温超导体和具有类似唯象性质的强相关材料的重要后果是预期的。