  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
$A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs) further pushes this topic to the quantum
frontier. Here we report the discovery and characterization of a new class of
vanadium-based compounds with kagome bilayers, namely $A$V$_6$Sb$_6$ ($A$ = K,
Rb, Cs) and V$_6$Sb$_4$, which, together with $A$V$_3$Sb$_5$, compose a series
of kagome compounds with a generic chemical formula
($A_{m-1}$Sb$_{2m}$)(V$_3$Sb)$_n$ (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 $A$V$_6$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.

Materials Science;Strongly Correlated Electrons;Superconductivity