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 8 Sb 12 and AV 6 Sb 6 (A = Cs, Rb), which have C 2 (space group: Cmmm ) and C 3 (space group: <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>R</mml:mi> <mml:mover accent="true"> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo stretchy="false">¯</mml:mo> </mml:mrow> </mml:mover> <mml:mi>m</mml:mi> </mml:math> ) symmetry, respectively. The basic V-kagome unit appears in both compounds, but stacking differently. A V 2 Sb 2 layer is sandwiched between two V 3 Sb 5 layers in AV 8 Sb 12 , altering the V-kagome lattice and lowering the symmetry of kagome layer from hexagonal to orthorhombic. In AV 6 Sb 6 , the building block is a more complex slab made up of two half-V 3 Sb 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 8 Sb 12 above 0.3 K under in situ pressure up to 46 GPa. Compared to CsV 3 Sb 5 , theoretical calculations and angle-resolved photoemission spectroscopy reveal a quasi-two-dimensional electronic structure in CsV 8 Sb 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.