Theoretical investigation of the phase diagram of high-Tc superconductors

高温超导体相图的理论研究

• 批准号: 5425103
• 负责人: Professor Dr. Werner Hanke
• 金额: --
• 依托单位: I. Institut für Theoretische Physik
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2004
• 资助国家: 德国
• 起止时间: 2003-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5425103?language=en
• 关键词: Theoretical; investigation; phase; diagram; Tc

The essential new point of this joint Forschergruppe is to study the global phase diagram of the high-temperature superconducting compounds and the competition between the different phases in a tightly coordinated effort between sample preparation, experiment and theoretical modeling. The different experimental techniques yield all essential information on the thermodynamics and the elementary excitations in these compounds. On the basis of a variety of complementary and partly new theoretical techniques, namely quantum Monte-Carlo (QMC), variational cluster techniques going to the infinite-lattice limit combined with QMC, and new contractor renormalizationgroup concepts (CORE), we will directly use this experimental input to clarify the at present still unresolved issue of what is of "general relevance" and what is more "material specific". This is a necessary precondition to answer, in a subsequent step and again in close connection with experiment, questions that are central for an understanding of the high-Tc phenomenon: Crucial questions to be investigated concern the asymmetry of the phase diagram (n- vs. p -doping), the relevant couplings of charge carriers to bosonic excitations, the role of electron-phonon interaction in the pairing mechanism, the nature of the pseudo-gap "phase", and, quite generally, the connection of the microscopic interactions at "high energy" (from eV to order J ) with the observed phases competing with each other at very low temperatures.

这个联合研究小组的基本新点是研究高温超导化合物的全局相图和不同相之间的竞争，在样品制备，实验和理论建模之间进行紧密协调。不同的实验技术产生的热力学和这些化合物中的元激发的所有重要信息。基于各种互补的和部分新的理论技术，即量子蒙特-卡罗（QMC），变分簇技术与QMC相结合的无限晶格极限，和新的承包商renormalizationgroup概念（CORE），我们将直接使用这个实验输入来澄清目前仍然悬而未决的问题，什么是“一般相关性”，什么是更“具体的材料”。这是一个必要的先决条件，在随后的步骤中，并再次与实验密切相关，回答问题，这些问题是理解高Tc现象的核心：要研究的关键问题涉及相图的不对称性（n-对p -掺杂），载流子与玻色子激发的相关耦合，电子-声子相互作用在配对机制中的作用，伪间隙“相”的性质，以及相当普遍地，在“高能量”（从eV到J级）下的微观相互作用与在非常低的温度下彼此竞争的观察到的相的连接。