Superconductivity Induced by Site-Selective Arsenic Doping in Mo$_5$Si$_3$

TL;DR

This study demonstrates that site-selective arsenic doping in Mo$_5$Si$_3$ induces superconductivity with a transition temperature of 7.7 K, highlighting a new method for Fermi level engineering in silicides.

Contribution

It introduces arsenic doping as a novel approach to induce superconductivity in Mo$_5$Si$_3$, with site-specific doping and detailed analysis of the resulting superconducting properties.

Findings

Superconductivity achieved at 7.7 K in As-doped Mo$_5$Si$_3$

As atoms selectively occupy 8h sites in the crystal structure

Superconductivity likely due to Fermi level shift from As doping

Abstract

Arsenic doping in silicides has been much less studied compared with phosphorus. In this study, superconductivity is successfully induced by As doping in Mo$_5$Si$_3$. The superconducting transition temperature ($T_c$) reaches 7.7 K, which is higher than those in previously known W$_5$Si$_3$-type superconductors. Mo$_5$Si$_2$As is a type-II BCS superconductor with upper and lower critical fields of 6.65 T and 22.4 mT, respectively. In addition, As atoms are found to selectively take the 8$h$ sites in Mo$_5$Si$_2$As. The emergence of superconductivity is possibly due to the shift of Fermi level as a consequence of As doping, as revealed by the specific heat measurements and first-principles calculations. Our work provides not only another example of As doping, but also a practical strategy to achieve superconductivity in silicides through Fermi level engineering.