Superconductivity well above room temperature in compressed MgH₆

Abstract

It has been suggested that hydrogen-rich systems at high pressure may exhibit notably high super-conducting transition temperatures. One of the more interesting theoretical predictions was that hydrogen sulfide can be metallized and the high-temperature superconducting state can be induced. A record critical temperature (203 K) was later confirmed for H₃S in an experiment. In this paper, we investigated, within the framework of the Eliashberg formalism, the properties of compressed MgH₆, which is expected to be a very good candidate for room-temperature superconductivity. This applies particularly to the pressure range from 300 to 400 GPa, where the transition temperature is close to 400 K. Moreover, the estimated thermodynamic properties and the resulting dimensionless ratios exceed the predictions of the Bardeen–Cooper–Schrieffer theory. This behavior is attributed to the strong electron–phonon coupling and retardation effects existing in hydrogen-dominated materials under high pressure.

Keywords

superconductors / hydrogen-rich compounds / high pressure / thermodynamic properties

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2016 Higher Education Press and Springer-Verlag Berlin Heidelberg