Electron-phonon coupling and superconductivity in an alkaline earth hydride CaH<sub>6</sub> at high pressures
نویسندگان
چکیده
Recently, an alkaline earth hydride CaH$_6$ having a sodalitelike clathrate structure has been experimentally synthesized at megabar pressures with maximum $T_c$ of 215 K, comparable to that rare LaH$_{10}$. Here, based on first-principles calculations, we find exhibits huge peak in the Eliashberg spectral function ${\alpha}^{2}F$ around low-frequency region H-derived phonon modes, contrast LaH$_{10}$ widely spreading spectrum over whole frequencies modes. It is revealed associated effective electron-phonon coupling (EPC) between optical phonons and hybridized H 1$s$ Ca 3$d$ states near Fermi energy. As pressure increases, strengthened H$-$H covalent bonding not only induces hardening modes but also reduces matrix elements related thereby leading lowering EPC constant. thus demonstrated play important role pressure-induced variation CaH$_6$. Furthermore, unlike presence two distinct superconducting gaps LaH$_{10}$, found exhibit single isotropic gap.
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ژورنال
عنوان ژورنال: New Journal of Physics
سال: 2022
ISSN: ['1367-2630']
DOI: https://doi.org/10.1088/1367-2630/ac8a0c