YRu 3 B 2 —a kagome lattice superconductor

Abstract We report the synthesis and physical properties of a hexagonal boride YRu 3 B 2 , which was previously predicted to show superconductivity [N.K. Nepal, L.-L. Wang, arXiv:2409.18441 (2024)]. A polycrystalline sample was synthesized by arc-melting a pre-reacted YB 2 and metallic Ru. Phase and elemental composition were characterized by means of powder x-ray diffraction and scanning electron microcopy. Our resistivity and heat capacity measurements indicate that YRu 3 B 2 is a weakly coupled superconductor, with a critical temperature T c = 0.63 K and an upper critical field μ 0 H c 2 ( 0 ) = 0.11 T. Isovalent substitution of Y with 5 at% and 10 at% of Sc resulted in a slight enhancement of the critical temperature up to ca. 0.8 K. Density functional theory calculations together with chemical-bonding analysis, reveal that the electronic states at and near the Fermi energy level are dominated by the Ru kagome sublattice.