压致铁磁量子临界材料CeRh6Ge4的4f电子行为特性研究

CeRh6Ge4是新发现的在压力调控下表现奇异金属行为的铁磁材料，它是目前发现的第一个具有低压(0.8GPa)铁磁量子临界点的纯净体系。因此，它为研究铁磁量子相变和奇异金属行为提供了新的研究平台和开辟了新的研究方向。然而，目前对它的理解主要是基于宏观物性测量，而微观研究才刚刚开始。CeRh6Ge4的奇异物性由4f电子在特定外界条件下的行为决定，因此本项目拟通过结合密度泛函理论(DFT)与动力学平均场理论(DMFT)来研究其4f电子行为：首先通过与LaRh6Ge4的对比研究来深入理解强关联效应对常压态CeRh6Ge4电子结构的影响；然后对等静压-温度相图中典型状态下的CeRh6Ge4开展与电子结构相关物理量的计算，研究在温度和压力诱导的局域-巡游转变过程中、铁磁转变前后4f电子特性的演化规律，为等静压-温度相图提供高置信度微观电子结构基础。本项目是进一步研究铁磁量子临界和奇异金属行为的基础。

Strange-metal behavior has been discovered recently in the pure ferromagnetic Kondo lattice CeRh6Ge4 at around a pressure-induced quantum critical point. Therefore, it promises a new direction for research into the ferromagnetic quantum phase transitions and establishes an alternative platform for investigation of the strange-metal phenomenon. The current understanding of CeRh6Ge4 is mostly based on the results from macroscopic measurements, and microscopic investigations of the physics underlying its properties are at the initial stage. The exotic physical properties of CeRh6Ge4 are governed by the behavior of 4f electrons. Therefore, this project aims to investigate the characters of 4f electrons across the pressure(P)-temperature (T) phase diagram, via the combination of first-principle density functional theory (DFT) and dynamical mean-field theory (DMFT). First, by comparing with LaRh6Ge4, the strong correlation effects of 4f electrons manifested on the electronic structure of CeRh6Ge4 are to be studied. Then, the characters of the 4f electrons during the P/T-induced localized-to-itinerant and ferromagnetic transition are to be studied, by calculating physical quantities related to electronic structure. This project is intended to provide faithful microscopic electronic structure basis for CeRh6Ge4 across the P-T phase diagram, which is fundamental for further understanding of the ferromagnetic quantum criticality and strange-metal phenomenon.