Phonon-mediated high-temperature superconductivity in ternary borohydride KB${}_2$H${}_8$ around 12 GPa

Abstract

Discovery of high-temperature superconductivity in hydrogen-rich compounds has fuelled the enthusiasm for finding materials with more promising superconducting properties among hydrides. However, the ultrahigh pressure needed to synthesize and maintain high-temperature hydrogen-rich superconductors hinders the experimental investigation of these materials. For practical applications, it is also highly desired to find more hydrogen-rich materials that superconduct at high temperatures but under relatively lower pressures. Based on first-principles density functional theory, we calculate the electronic and phonon band structures for a ternary borohydride formed by intercalating BH${}_4$ tetrahedrons into a face-centered-cubic potassium lattice, KB${}_2$H${}_8$. Remarkably, we find that this material is dynamically stable and one of its $s{p}^3$-hybridized $\sigma$-bonding bands is metallized (i.e. partially filled) above a moderate high pressure. This metallized $\sigma$-bonding band couples strongly with phonons, giving rise to a strong superconducting pairing potential. By solving the anisotropic Eliashberg equations, we predict that the superconducting transition temperature of this compound is 134-146 K around 12 GPa.

5 pages, 4 figures

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Cited by in corpus (4)

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• Materials under high pressure: A chemical perspective
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• Quantum and temperature effects on crystal structure of superhydride: A path integral molecular dynamics study