Electron- and hole-doping on ScH₂and YH₂: effects on superconductivity without applied pressure

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Metal hydrides like ScH2 and YH2 are promising for superconductivity.
• Tuning their properties through doping is crucial for enhancing performance.

Purpose of the Study:

• Investigate the impact of electron and hole doping on ScH2 and YH2.
• Determine how doping affects structural, electronic, and lattice dynamical properties.
• Optimize electron-phonon coupling and superconducting critical temperature (Tc).

Main Methods:

• Density Functional Perturbation Theory (DFPT).
• Quasi-Harmonic Approximation (QHA) for zero-point energy.
• Virtual Crystal Approximation (VCA) for solid solutions.

Main Results:

• Hole-doping (Ca, Sr) did not improve electron-phonon coupling (λ).
• Electron-doping (Ti, Zr) at x ≈ 0.5 triggered latent coupling, increasing λ by up to 70%.
• Tc decreased with hole-doping but showed a minimum at x=0.5 with electron-doping, then rapidly increased.

Conclusions:

• Electron-doping is a viable strategy to enhance superconductivity in ScH2 and YH2.
• Hole-doping negatively impacts superconducting properties.
• Optimized electron-doping in Sc0.05Ti0.95H2 and Y0.2Zr0.8H2 yields maximum Tc without applied pressure.