Superconductivity Induced by Site-Selective Arsenic Doping in Mo₅Si₃

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Superconductivity in silicides remains less explored compared to other dopants.
• Phosphorus doping in silicides is more studied than arsenic doping.
• Previous W5Si3-type superconductors exhibit lower transition temperatures.

Purpose of the Study:

• To investigate superconductivity induced by arsenic (As) doping in molybdenum silicide (Mo5Si3).
• To characterize the superconducting properties of the As-doped Mo5Si3 compound.
• To explore the mechanism behind the induced superconductivity via Fermi level engineering.

Main Methods:

• Arsenic doping of Mo5Si3.
• Superconducting transition temperature (Tc) measurements.
• Determination of upper and lower critical fields.
• X-ray diffraction for site occupancy analysis.
• Specific heat measurements.
• First-principles calculations.

Main Results:

• Superconductivity was successfully induced in Mo5Si2As with a Tc of 7.7 K.
• Mo5Si2As exhibits type-II BCS superconducting behavior with critical fields of 6.65 T and 22.4 mT.
• Arsenic atoms selectively occupy the 8h sites in the Mo5Si2As crystal structure.
• Fermi level shift due to As doping is identified as the likely cause of superconductivity.

Conclusions:

• Arsenic doping is a viable route to achieve superconductivity in silicides.
• Mo5Si2As represents a new class of superconductors with a notable Tc.
• Fermi level engineering offers a practical strategy for designing novel superconducting materials.