Prediction of ambient superconductivity in ternary thorium-silicon superhydrides with a breathing kagome lattice

Abstract

A major focus of current research on superconducting superhydrides is to achieve superconductivity at lower pressures, especially ambient pressure. Here we present the prediction of a class of high-temperature ternary hydrogen-rich superconductors, which are metastable at mild pressure and dynamically stable at ambient pressure using crystal structure searching. Our findings reveal the existence of a hexagonal ThSiH7 compound with a superconducting Tc of 61.5 K at ambient pressure, as estimated by electron-phonon coupling calculations. Interestingly, the H sites in ThSiH7 materialize a breathing kagome network, equivalent to a triangular lattice of trimer plaquettes, which is entirely different from previously known hydrogen clathrate structures. By substituting Th with lanthanide elements, we discovered that LaSiH7 and CeSiH7 are also dynamically stable at 0 GPa, while PrSiH7 and NdSiH7 are dynamically stable at 10 and 15 GPa with high Tc values of 63.9 and 65.9 K, respectively. Our results provide a system for superconducting hydrides and open a promising avenue for studying ambient pressure high-temperature superconductors.

Source-reported materials — not catalogue approval

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