Discovery of Two Families of VSb-Based Compounds with V-Kagome Lattice

We report the structure and physical properties of two newly discovered compounds AV_8Sb_12 and AV_6Sb_6 (A = Cs, Rb), which have C_2 (space group: Cmmm) and C_3 (space group: R\bar3m) symmetry, respectively. The basic V-kagome unit appears in both compounds, but stacking differently. A V_2Sb_2 layer is sandwiched between two V_3Sb_5 layers in AV_8Sb_12, altering the V-kagome lattice and lowering the symmetry of kagome layer from hexagonal to orthorhombic. In AV_6Sb_6, the building block is a more complex slab made up of two half-V_3Sb_5 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 10^21 cm^-3. No superconductivity has been observed in CsV_8Sb_12 above 0.3 K under in situ pressure up to 46 GPa. Compared to CsV_3Sb_5, theoretical calculations and angle-resolved photoemission spectroscopy reveal a quasi-two-dimensional electronic structure in CsV_8Sb_12 with C_2 symmetry and no van Hove singularities near the Fermi level. Our findings will stimulate more research into V-based kagome quantum materials.