Effect of Disorder on Superconductivity in TlNi$_2$Se$_{2-x}$S$_x$ crystals    [PDF]

Hangdong Wang, Chiheng Dong, Qianhui Mao, Rajwali Khan, Xi Zhou, Chenxia Li, Bin Chen, Jinhu Yang, Minghu Fang
After our first discovery of the multi-band superconductivity (SC) in TlNi$_2$Se$_2$ crystal, we grew successfully a series of TlNi$_2$Se$_{2-x}$S$_x$ (0.0 $\leq$ x $\leq$2.0) single crystals. The measurements of resistivity, specific heat and susceptibility were carried out for them. Superconductivity with $T_C$=2.3K was first observed in TlNi$_2$S$_2$ crystal, which also appears to involve heavy electrons with an effective mass $m^*$=13$\sim$25 $m_b$, as inferred from the normal state electronic specific heat and the upper critical field, $H_{C2}(T)$. It was found that the $T_C$ value in the TlNi$_2$Se$_{2-x}$S$_x$ crystals changes with the disorder degree induced by the partial substitution of S for Se with the same valence, which can be characterized by the residual resistivity ratio (RRR). Thus, TlNi$_2$Se$_{2-x}$S$_x$ system provides a platform to study the effect of disorder on the multi-band superconductivity.
View original: http://arxiv.org/abs/1305.1033