High-pressure synthesis of superconducting clathratelike YH4

Abstract

Pursuing room-temperature superconductors has been a major theme in physics and material sciences since the discovery of superconductivity in 1911. In light of the tremendous progress that has been made in hydrogen-based superconductors with record Tc∼260K in binary fcc LaH10, it is natural to explore more similar phases in hydrogen-rich materials. Y and La are conventionally grouped together with the lanthanide elements due to the similarities in their outer electron configurations and properties. The yttrium-hydrogen system is the most attractive candidate with high Tc among all binary metal-hydrogen systems theoretically studied so far. Here we report the synthesis of the I4/mmm−YH4 phase and determine its superconducting transition with maximum Tc∼88K at 155 GPa. The decrease in critical temperature under an external magnetic field suggests the upper critical magnetic field of about 14–22 T at megabar pressures consistent with theoretical data. By making the overlapping analysis, we elucidate that the stabilization of clathrate structures through Y atoms and the high-frequency hydrogen sublattice vibrations contribute effectively to strong electron-phonon coupling and therefore high-temperature superconductivity in the I4/mmm−YH4 and Im3¯m−YH6 phases.

Source-reported materials — not catalogue approval

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