  We report the structure and physical properties of two newly-discovered
compounds AV8Sb12 and AV6Sb6 (A = Cs, Rb), which have C2 (space group: Cmmm)
and C3 (space group: R-3m) symmetry, respectively. The basic V-kagome unit is
present in both compounds, but stacking differently. A V2Sb2 layer is
sandwiched between two V3Sb5 layers in AV8Sb12, altering the V-kagome lattice
and lowering the symmetry of kagome layer from hexagonal to orthorhombic. In
AV6Sb6, the building block is a more complex slab made up of two half-V3Sb5
layers that are intercalated by Cs cations along the c-axis. Transport property
measurements demonstrate that both compounds are nonmagnetic metals, with
carrier concentrations at around 1021cm-3. No superconductivity has been
observed in CsV8Sb12 above 0.3 K under in-situ pressure up to 46 GPa. In
contrast to CsV3Sb5, theoretical calculations and angle-resolved photoemission
spectroscopy (ARPES) reveal a quasi-two-dimensional electronic structure in
CsV8Sb12 with C2 symmetry and no van Hove singularities near the Fermi level.
Our findings will stimulate more research into V-based kagome quantum
materials.
