The kagomé metals RbTi3Bi5 and CsTi3Bi5

Abstract

Abstract The kagomé metals RbTi3Bi5 and CsTi3Bi5 were synthesized both as polycrystalline powders by heating the elements in an argon atmosphere and as single crystals grown using a self-flux method. The compounds crystallize in the hexagonal crystal system isotypically to KV3Sb5 (P6/mmm, Z = 1, CsTi3Bi5: a = 5.7873(1), c = 9.2062(1) Å; RbTi3Bi5: a = 5.773(1), c = 9.065(1) Å). The titanium atoms form a kagomé net with bismuth atoms in the hexagons as well as above and below the triangles. The alkali metal atoms are coordinated by 12 bismuth atoms and form AlB2-like slabs between the kagomé layers. Magnetic susceptibility measurements with CsTi3Bi5 and RbTi3Bi5 single crystals reveal Pauli-paramagnetism and traces of superconductivity caused by CsBi2/RbBi2 impurities. Magnetotransport measurements reveal conventional Fermi liquid behavior and quantum oscillations indicative of a single dominant orbit at low temperature. DFT calculations show the characteristic metallic kagomé band structure similar to that of CsV3Sb5 with reduced band filling. A symmetry analysis of the band structure does not reveal an obvious and unique signature of a nontrivial topology.