Superconductivity in kagome metal ThRu3Si2

We report the physical properties of ThRu3Si2 featured with distorted Ru kagome lattice.The combined experiments of resistivity,magnetization and specific heat reveal bulk superconductivity with Te=3.8 K.The specific heat jump and calculated electron-phonon coupling indicate a moderate coupled BCS superconductor.In comparison with LaRu3Si2,the calculated electronic structure in ThRu3Si2 shows an electron-doping effect with electron filling lifted from 100 meV below flat bands to 300 meV above it.This explains the lower superconducting transition temperature and weaker electron correlations observed in ThRu3Si2.Our work suggests the Tc and electronic correlations in the kagome superconductor could have an intimate connection with the flat bands.