上海科技大学知识管理系统

We report electrical and thermal transport properties of single-crystalline kagome metals ATi3Bi5(A=Rb,Cs). Different from the structrually similar kagome superconductors AV3Sb5, no charge density wave instabilities are found in ATi3Bi5. At low temperatures below 5 K, signatures of superconductivity appear in ATi3Bi5 as seen in magnetization measurements. However, bulk superconductivity is not evidenced by specific heat results. Similar to AV3Sb5, ATi3Bi5 show a nonlinear magnetic field dependence of the Hall effect below about 70 K, pointing to a multiband nature. Unlike AV3Sb5 in which phonons and electron-phonon coupling play important roles in thermal transport, the thermal conductivity in ATi3Bi5 is dominated by electronic contributions. Moreover, our calculated electronic structures of ATi3Bi5 suggest that van Hove singularities are sitting well above the Fermi energy. Compared with AV3Sb5, the absence of charge orders in ATi3Bi5 is closely associated with minor contributions from electron-phonon coupling and/or van Hove singularities. © 2023 American Physical Society.