Superconductivity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>TlBi</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> with a large Kadowaki-Woods ratio
Zhihua Yang, Zhen Yang, Qi-Ping Su, Enda Fang, Jinhu Yang, Bin Chen, Hangdong Wang, Jianhua Du, Chunxiang Wu, Minghu Fang
Abstract
In this paper, the superconducting and normal state properties of ${\mathrm{TlBi}}_{2}$ with the ${\mathrm{AlB}}_{2}$-type structure were studied by resistivity, magnetization, and specific heat measurements. It was found that bulk superconductivity with ${T}_{c}=6.2$ K emerges in ${\mathrm{TlBi}}_{2}$, which is a phonon-mediated $s$-wave superconductor with a strong electron-phonon coupling (${\ensuremath{\lambda}}_{ep}=1.38$) and a large superconducting gap (${\mathrm{\ensuremath{\Delta}}}_{0}/{k}_{B}{T}_{c}=2.25$). We found that the $\ensuremath{\rho}(T$) exhibits an unusual $T$-linear dependence above 50 K, and can be well described by the Fermi-liquid theory below 20 K. Interestingly, its Kadowaki-Woods ratio $A/{\ensuremath{\gamma}}^{2} [9.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}\phantom{\rule{4pt}{0ex}}\mathrm{\textmu{}\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\text{cm}{(\text{mol}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{2}/\mathrm{mJ})}^{2}]$ is unexpectedly one order of magnitude larger than that obtained in many heavy fermion compounds, although the electronic correlation is not so strong.