We report electrical and thermal transport properties of single-crystalline kagome metals $A{\text{Ti}}_3{\text{Bi}}_5(A=\text{Rb},\mathrm{Cs})$. Different from the structrually similar kagome superconductors $A{\mathrm{V}}_3{\mathrm{Sb}}_5$, no charge density wave instabilities are found in $A{\mathrm{Ti}}_3{\mathrm{Bi}}_5$. At low temperatures below 5 K, signatures of superconductivity appear in $A{\mathrm{Ti}}_3{\mathrm{Bi}}_5$ as seen in magnetization measurements. However, bulk superconductivity is not evidenced by specific heat results. Similar to $A{\mathrm{V}}_3{\mathrm{Sb}}_5, A{\mathrm{Ti}}_3{\mathrm{Bi}}_5$ show a nonlinear magnetic field dependence of the Hall effect below about 70 K, pointing to a multiband nature. Unlike $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ in which phonons and electron-phonon coupling play important roles in thermal transport, the thermal conductivity in $A{\mathrm{Ti}}_3{\mathrm{Bi}}_5$ is dominated by electronic contributions. Moreover, our calculated electronic structures of ${\mathrm{ATi}}_3{\mathrm{Bi}}_5$ suggest that van Hove singularities are sitting well above the Fermi energy. Compared with $A{\mathrm{V}}_3{\mathrm{Sb}}_5$, the absence of charge orders in $A{\mathrm{Ti}}_3{\mathrm{Bi}}_5$ is closely associated with minor contributions from electron-phonon coupling and/or van Hove singularities.

• Received 7 March 2023
• Revised 25 April 2023
• Accepted 26 April 2023

DOI:https://doi.org/10.1103/PhysRevB.107.174510