Phenomenology of high-temperature superconducting cuprates: microscopic approach from weak coupling

本项目建议书包含三个子项目。在前两个子项目中，高温超导体物理学的两个重要问题，即欠掺杂系统中赝隙的性质和晶格振动的作用，将使用功能重正化群技术从理论上解决。这种方法对于弱到中度的相互作用是有充分根据的，并且能够平等地对待竞争性的相互作用。我们的目标是获得定性的见解，可以用来理解实验现象学，并帮助解释其他更复杂的理论方法在更强的相互作用下的结果。为了更好地描述赝隙中的光谱数据，以及自旋涨落与不同类型声子之间的相互作用，本文给出了各自的例子。在第三个子项目中，将开发量子蒙特卡罗和功能重整化群技术的结合，目标是将上述描述扩展到更强的相互作用。

This project proposal contains three sub-projects. In the first two sub-projects, two important issues of the physics of high-temperature superconductors, the nature of the pseudogap in underdoped systems and the role of lattice vibrations, will be addressed theoretically using functional renormalization group techniques. This approach is well-founded for weak to moderate interactions and is capable to treat competing interactions on equal footing. Our aim is to obtain qualitative insights which can be used to understand the experimental phenomenology and to help interpreting results of other, more involved theoretical approaches at stronger interactions. Respective examples are ans¨atze for a better characterization of spectral data in the pseudogap regime and the mutual interactions between spin fluctuations and different types of phonons. In a third sub-project, the combination of Quantum Monte-Carlo and functional renormalization group techniques shall be developed with the goal to extend the above-mentioned description toward stronger interactions.