In-silico synthesis of lowest-pressure high-$T_\text{c}$ ternary superhydrides

Roman Lucrezi; Simone Di Cataldo; Wolfgang von der Linden; Lilia Boeri; Christoph Heil

doi:10.1038/s41524-022-00801-y

paper

In-silico synthesis of lowest-pressure high- $T_{c}$ ternary superhydrides

arXiv:2112.02131 · doi:10.1038/s41524-022-00801-y

Abstract

We report the theoretical prediction of two high-performing hydride superconductors BaSiH $_{8}$ and SrSiH $_{8}$ . They are thermodynamically stable above pressures of $130$ and $174 GPa$ , respectively, and metastable below that. Employing anharmonic phonon calculations, we determine the minimum pressures of dynamical stability to be around $3 GPa$ for BaSiH $_{8}$ and $27 GPa$ for SrSiH $_{8}$ , and using the fully anisotropic Migdal-Eliashberg theory, we predict $T_{c}$ 's around $71$ and $126 K$ , respectively. We also introduce a method to estimate the lowest pressure of synthesis, based on the calculation of the enthalpy barriers protecting the BaSiH $_{8}$ $F m 3 ˉ m$ structure from decomposition at various pressures. This $k in e t i c$ pressure threshold is sensibly higher than the one based on $d y nami c$ stability, but gives a much more rigorous limit for synthesizability.

9 pages, 6 figures. Revised manuscript with minor changes. Supplemental Material available on the journal website (open access)

In-silico synthesis of lowest-pressure high-Tc​ ternary superhydrides

Abstract

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In-silico synthesis of lowest-pressure high- $T_{c}$ ternary superhydrides