Superconductivity Induced by Site-Selective Arsenic\nDoping in Mo₅Si₃

Abstract

Arsenic\ndoping in silicides has been much less studied compared\nwith phosphorus. In this study, superconductivity is successfully\ninduced by As doping in Mo₅Si₃. The superconducting\ntransition temperature (<i>T</i>_<i>c</i>) reaches 7.7 K, which is higher than those in previously known W₅Si₃-type superconductors. Mo₅Si₂As is a type-II BCS superconductor with upper and lower critical\nfields of 6.65 T and 22.4 mT, respectively. In addition, As atoms\nare found to selectively take the 8<i>h</i> sites in Mo₅Si₂As. The emergence of superconductivity is possibly\ndue to the shift of Fermi level as a consequence of As doping, as\nrevealed by the specific heat measurements and first-principles calculations.\nOur work provides not only another example of As doping but also a\npractical strategy to achieve superconductivity in silicides through\nFermi level engineering.