Computational study of pressurized tetragonal magnesium hydride (MgH4) as a potential candidate for high-temperature superconducting material

Abstract

The dream of realizing room temperature superconductivity is one of the most challenging problems in condensed matter physics. Currently, materials with dense hydrogen contents at high pressures hold great promise for realizing room temperature superconductivity. In particular, pressurized alkaline earth metal hydrides received particular attention following the recently predicted sodalite-like calcium hydride (CaH _6 ) with predicted Tc about 261 K above a pressure of 150 GPa; and magnesium hydride (MgH _6 ) with predicted Tc about 270 K above 300 GPa. In this paper, we studied magnesium hydride (MgH _4 ) with tetragonal (I4/mmm) type symmetry, and we found that this structure shows the highest ${T}_{c}\cong 313K$ at a pressure of 280 GPa which is higher than that of MgH _6 . Using density-functional perturbation theory (DFPT), the superconducting transition temperature, electron-phonon coupling, Eliashberg spectral function, and the logarithmic average frequency were computed. Our results reveal that, the computed values are reasonably in agreement with previous estimates.

Keywords

• electron-phonon coupling
• electronic band
• high-temperature superconductivity
• magnesium hydrides
• metalization pressure
• phonon band dispersion