Density wave-like behavior in a kagome material, Ce2Ru3Si

<h2>Summary</h2> Kagome materials with inherent geometric frustration can produce many interesting physical properties, such as flat bands, superconductivity, and density-wave orders. In this study, we present a kagome material, Ce₂Ru₃Si, containing the Ru kagome planes. Electrical transport and specific heat measurements reveal a density wave-like transition. The calculated Wilson ratio <mml:math><mml:mrow><mml:mi>R</mml:mi><mml:mi>W</mml:mi><mml:mo>∝</mml:mo><mml:mi>χ</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mn>0</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mo>/</mml:mo><mml:mi>γ</mml:mi><mml:mi>n</mml:mi></mml:mrow></mml:math> is approximately 2.82, 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 exhibits a Mexican hat-shaped band near the Fermi level, which may be potentially related to the observed transition. Additionally, the calculated Fermi surface shows obvious nesting feature, and an evident negative phonon exists in phonon dispersion. These two effects are most likely the driving forces for the transition. Our findings provide a useful platform for investigating the relationship between the density-wave transition and kagome structure.