Electrical and thermal transport properties of the kagome metals <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>A</mml:mi><mml:msub><mml:mtext>Ti</mml:mtext><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mtext>Bi</mml:mtext><mml:mn>5</mml:mn></mml:msub></mml:mrow><mml:mspace width="4pt"/><mml:mo>(</mml:mo><mml:mrow><mml:mi>A</mml:mi><mml:mo>=</mml:mo><mml:mtext>Rb</mml:mtext></mml:mrow><mml:mo>,</mml:mo><mml:mspace width="4pt"/><mml:mi>Cs</mml:mi><mml:mo>)</mml:mo></mml:math>
Xintong Chen, Xiangqi Liu, Wei Xia, Xinrun Mi, Luyao Zhong, Kunya Yang, Long Zhang, Yuhan Gan, Yan Liu, Guiwen Wang, Aifeng Wang, Yisheng Chai, Junying Shen, Xiaolong Yang, Yanfeng Guo, Mingquan He
Abstract
We report electrical and thermal transport properties of single-crystalline kagome metals $A{\text{Ti}}_{3}{\text{Bi}}_{5}\phantom{\rule{4pt}{0ex}}(A=\text{Rb},\phantom{\rule{4pt}{0ex}}\mathrm{Cs})$. 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.