• DOI:10.1103/PhysRevMaterials.3.084603
• Corpus ID: 195766907

Superconducting phase diagram and nontrivial band topology of structurally modulated Sn1−xSbx

@article{Liu2019SuperconductingPD,
  title={Superconducting phase diagram and nontrivial band topology of structurally modulated 
Sn1−xSbx},
  author={Bin Liu and Chengcheng Xiao and Qinqing Zhu and Jifeng Wu and Yan-Wei Cui and Hangdong Wang and Zhicheng Wang and Yunhao Lu and Zhi-An Ren and Guanghan Cao},
  journal={Physical Review Materials},
  year={2019}
}

• Bin Liu, C. Xiao, +7 authors G. Cao
• Published 30 June 2019
• Physics, Materials Science
• Physical Review Materials

We report the discovery of superconductivity in binary alloy Sn$_{1-x}$Sb$_{x}$ with $x$ in the range of 0.43 to 0.6, which possesses a modulated rhombohedral structure due to the incommensurate ordering of Sn and Sb layers along the $c$-axis. The specific heat measurements indicate a weakly coupled, fully gapped superconducting state in this homogeneity range with a maximum bulk $T_{\rm c}$ of 1.58 K at $x$ = 0.46, though the electronic specific heat and Hall coefficients remain nearly $x$-independent. The nonmonotonic dependence of the bulk $T_{\rm c}$ is discussed in relation to the effects of Sb-layer intercalation between the [Sn$_{4}$Sb$_{3}$] seven-layer lamellae that are the essential building block for superconductivity. On the other hand, a zero-resistivity transition is found to take place well above the bulk superconducting transition, and the corresponding $T_{\rm c}$ increases monotonically with $x$ from 2.06 K to 3.29 K. This contrast, together with the uniform elements distribution revealed by energy dispersive x-ray mapping, implies that the resistive transition is due to the strain effect at the grain boundary rather than the compositional inhomogeneity. The first-principles calculations on the representative composition Sn$_{4}$Sb$_{3}$ ($x$ = 0.43) indicate that it is topologically nontrivial similar to Sb, but with different Z$_{2}$ invariants (0;111). Our results not only identify a new superconducting region in the Sn-Sb phase diagram, but also provide a viable platform to study the interplay between structural modulation, nontrivial band topology and superconductivity.