Superconductivity on ScH${}_3$ and YH${}_3$ hydrides: Effects of applied pressure in combination with electron- and hole-doping on the electron-phonon coupling properties

Abstract

The implementation of electron- and hole-doping, in conjunction to applied pressure, is analyzed as a mechanism to induce or enhance the superconducting state on fcc YH${}_3$ and ScH${}_3$. In particular, the evolution of their structural, electronic, and lattice dynamical properties, as well as the electron-phonon coupling and superconducting critical temperature ($T_c$) is presented and discussed, as a function of the electron- and hole-doping content as well as applied pressure. The study was performed within the density functional perturbation theory, taking into account the effects of zero-point energy through the quasi-harmonic approximation, while the doping was implemented by means of the construction of the Sc${}_{1-x}$M${}_x$H${}_3$ (M=Ca,Ti) and Y${}_{1-x}$M${}_x$H${}_3$ (M=Sr,Zr) solid solutions modeled with the virtual crystal approximation (VCA). We found that the ScH${}_3$ and YH${}_3$ hydrides shown a significant improvement of their electron-phonon coupling properties under hole-doping (M=Ca,Sr) and at pressure values close to dynamical instabilities. Instead, by electron-doping (M=Ti,Zr), the systems do not improve such properties, whatever value of applied pressure is considered. Then, as a result, $T_c$ rapidly increases as a function of $x$ on the hole-doping region, reaching its maximum value of $92.7(67.9)$~K and $84.5(60.2)$~K at $x=0.3$ for Sc${}_{1-x}$Ca${}_x$H${}_3$ at $10.8$~GPa and Y${}_{1-x}$Sr${}_x$H${}_3$ at $5.8$~GPa respectively, with ${\mu }^{\ast }=0(0.15)$, while for both, electron- and hole-doping, $T_c$ decreases as a function of the applied pressure, mainly due to phonon hardening. By the thorough analysis of the electron-phonon properties as a function of doping and pressure, we can conclude that the tuning of the lattice dynamics is a promising path for improving the superconductivity on both systems.

12 pages, 12 figures, 1 table

References in corpus (6)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Superconductive "sodalite"-like clathrate calcium hydride at high pressures
• Superconductivity to 262 kelvin via catalyzed hydrogenation of yttrium at high pressures
• Three-dimensional MgB${}_2$-type superconductivity in hole-doped diamond
• Electron-phonon coupling mechanisms for hydrogen-rich metals at high pressure
• Electron- and hole-doping on ScH${}_2$ and YH${}_2$: Effects on superconductivity without applied pressure

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