A $2\times2\times2$ charge density wave (CDW) was recently observed deep inside the antiferromagnetic phase of a Kagome metal FeGe. A key question is whether the CDW in FeGe is driven by its electronic correlation and magnetism. Here, we address this problem using density functional theory and its combination with $U$ as well as dynamical mean-field theory. Our calculations show that large dimerization ($\sim 1.3 \overset{\lower.5em\circ}{\mathrm{A}}$) of Ge1-sites along $c$-axis will enhance electronic correlation of the Fe-$3d$ orbitals and, as a result, it enhances the spin-polarization and saves more magnetic exchange energies. We find that the balance between magnetic energy saving and structural energy cost via partially dimerizing Ge1-sites in an enlarged superstructure, could induce a new local minimum in total energies. The response to the large partial Ge1-dimerization will induce additional small modulations ($<0.05 \overset{\lower.5em\circ}{\mathrm{A}}$) of other sites in the Kagome and honeycomb layers, which further reduces the total energy and leads to a stable $2\times 2\times 2$ CDW ground state in FeGe. Our results are in good agreement with the existing experiments and reveal a novel CDW mechanism driven by the interplay of structure, electronic correlation and magnetism.
Phonons and magnetism of kagome FeGe probed by nuclear resonant scattering
Center for Correlated Matter and School of Physics, Zhejiang University（浙江大学相关物质研究中心和物理学院）；Department of Physics and Astronomy, Rice University（莱斯大学物理与天文学系）；Rice Laboratory for Emergent Magnetic Materials and Smalley-Curl Institute, Rice University（莱斯大学涌现磁性材料实验室及Smalley-Curl研究所）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器研究所）；School of Emerging Technology, University of Science and Technology of China（中国科学技术大学前沿技术学院）；Hefei National Laboratory（合肥国家实验室）；New Cornerstone Science Laboratory, University of Science and Technology of China（中国科学技术大学新基石科学实验室）
Orbital-selective band evolution and out-of-plane correlation in the FeGe-family kagome antiferromagnet ScFe$_6$Ge$_6$
Seoul National University（首尔大学）；ShanghaiTech University（上海科技大学）；University of Science and Technology of China（中国科学技术大学）；Sejong University（世宗大学）；Korea Institute of Science and Technology（韩国科学技术院）；National Institutes for Quantum Science and Technology（量子科学技术研究机构）；Shanghai Advanced Research Institute, Chinese Academy of Sciences（中国科学院上海高等研究院）
