Density-wave like behavior in a new Kagome material Ce$_{2}$Ru$_{3}$Si

TL;DR

This study introduces a new kagome material Ce$_{2}$Ru$_{3}$Si exhibiting density-wave-like behavior, with experimental and theoretical evidence suggesting electron correlations and Fermi surface features driving the transition.

Contribution

The paper reports the discovery and characterization of a novel kagome compound Ce$_{2}$Ru$_{3}$Si, revealing density-wave-like transition behavior linked to its electronic structure.

Findings

Density-wave-like transition observed via transport and heat measurements.

Doping effects show suppression or decrease of the transition temperature.

Electronic structure calculations reveal a Mexican-hat-shaped Fermi surface.

Abstract

Kagome materials with inherent geometric frustration can produce many interesting physical properties, such as flat bands, quantum spin liquid, chiral magnetism, superconductivity and density-wave orders. Sometimes, the localized 4$f$ electrons from Ce atoms coupled with other conduction electrons would also give rise to the flat bands near the Fermi level, and results in the formation of heavy fermion. Thus, it is highly probable that kagome material incorporating Ce element will display nontrivial physical properties. In this study, we present a new Kagome material belonging to the trinary Laves phase, Ce$_{2}$Ru$_{3}$Si, in which kagome plane is formed by Ru atoms. Electrical transport and specific heat measurements reveal a density-wave like transition. A Curie-Weiss behavior is observed in low-temperature region. Meanwhile we also find a relatively large specific coefficient $\gamma_{n}(0)$. The calculated Wilson ratio $R_\mathrm{W}\propto{\chi(0)/\gamma_{n}}$ is approximately 3.1, indicating a moderate electron correlation effect. Chemical doping of Ir at the Ru site rapidly suppresses this density-wave like transition, while Mo doping leads to a gradual decrease in transition temperature. Theoretical calculation indicates both the Ce-4$f$ and Ru-4$d$ electronic bands cross the Fermi level, forming a Mexican-hat-shape Fermi surface close to the Fermi energy, potentially accounting for the observed density-wave like transition. Our findings provide an useful platform for investigating how hybridization between 4$f$ and 4$d$ electrons influences the electronic transport, and the relationship between the density-wave transition and kagome structure.