A new class of bilayer kagome lattice compounds with Dirac nodal lines and pressure-induced superconductivity

Kagome lattices composed of transition-metal ions have recently attracted great interest. Here, the authors report a new class of vanadium-based compounds with kagome bilayers which show lines of Dirac nodes in reciprocal space and superconductivity under pressure. Kagome lattice composed of transition-metal ions provides a great opportunity to explore the intertwining between geometry, electronic orders and band topology. The discovery of multiple competing orders that connect intimately with the underlying topological band structure in nonmagnetic kagome metals AV(3)Sb(5) (A = K, Rb, Cs) further pushes this topic to the quantum frontier. Here we report a new class of vanadium-based compounds with kagome bilayers, namely AV(6)Sb(6) (A = K, Rb, Cs) and V6Sb4, which, together with AV(3)Sb(5), compose a series of kagome compounds with a generic chemical formula (A(m-1)Sb(2m))(V3Sb)(n) (m = 1, 2; n = 1, 2). Theoretical calculations combined with angle-resolved photoemission measurements reveal that these compounds feature Dirac nodal lines in close vicinity to the Fermi level. Pressure-induced superconductivity in AV(6)Sb(6) further suggests promising emergent phenomena in these materials. The establishment of a new family of layered kagome materials paves the way for designer of fascinating kagome systems with diverse topological nontrivialities and collective ground states.

Automated summary

The authors report a new class of vanadium-based compounds with kagome bilayers that exhibit Dirac nodal lines and superconductivity under pressure. The discovery of these materials provides an opportunity to explore the intertwining between geometry, electronic orders, and band topology.