Computational prediction of new stable superconducting magnesium hydrides at high-pressures

Abstract

Because of its potential use for technological applications, realization of high-temperature superconductivity is one of the greatest goals of physics. In particular, if superconductivity at (or near) room-temperature is realized, it can dramatically revolutionize technology which can benefit the daily life of mankind. One of the methods which received particular attention to scientists is to compress dense-hydrogen containing compounds at high-pressures. In this paper, we explored new stable superconducting magnesium hydrides by using first-principle calculations. Using the open source quantum ESPRESSO software package, we report new stable phases of magnesium hydrides. We studied magnesium hydrides with different structures; and we found that, next to the previously predicted tetragonal (I4/mmm) type MgH4, another MgH4 with P63/mmc (hexagonal) type symmetry also show an estimated superconducting temperature up to 280 K at a pressure of about 301 GPa. After carefully analyzing the electronic band structure, density of electronic states, and other properties of each structure, we calculated the superconducting temperature, electron-phonon coupling constant, Eliashberg spectral function, and other vibrational properties of each predicted structure. Our calculated values are consistent with experimental observations.