Electronic correlation effects on stabilizing a perfect Kagome lattice and ferromagnetic fluctuation in LaRu₃Si₂

A perfect Kagome lattice features flat bands that usually lead to strong electronic correlation effects, but how electronic correlation, in turn, stabilizes a perfect Kagome lattice has rarely been explored. Here, we study this effect in a superconducting (T_\rmc \sim 7.8 K) Kagome metal LaRu₃Si₂ with a distorted Kagome plane consisting of pure Ru ions, using density functional theory plus U and plus dynamical mean-field theory. We find that increasing electronic correlation can stabilize a perfect Kagome lattice and induce substantial ferromagnetic fluctuations in LaRu₃Si₂. By comparing the calculated magnetic susceptibilities to experimental data, LaRu₃Si₂ is found to be on the verge of becoming a perfect Kagome lattice. It thus shows moderate but non-negligible electronic correlations and ferromagnetic fluctuations, which are crucial to understand the experimentally observed non-Fermi-liquid behavior and the pretty high superconducting T_\rmc of LaRu₃Si₂.