Superconductivity in CaH$_{6}$ and ThH$_{10}$ through fully ab initio Eliashberg method and self-consistent Green’s function

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2024年8月8日

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Alwan Abdillah Darussalam,
Takashi Koretsune

摘要

Pressurized hydrogen-based superconductors are phonon-mediated superconductors that exhibit high phonon frequencies. In these superconductors, in addition to the density of states (DOS) at the Fermi energy ( $E_F$ $E_{F}$ ), the energy dependence of the DOS around $E_F$ $E_{F}$ becomes important for evaluating their transition temperature ( $T_c$ $T_{c}$ ). Systems with peak structures in the DOS around $E_F$ $E_{F}$ , such as $Im\bar{3}m$ $I m \bar{3} m$ H $_{3}$ $_{3}$ S and $Fm\bar{3}m$ $F m \bar{3} m$ LaH $_{10}$ $_{10}$ , highlight this point. We use the fully ab initio Eliashberg method to investigate this phenomenon in $Im\bar{3}m$ $I m \bar{3} m$ CaH $_{6}$ $_{6}$ and $Fm\bar{3}m$ $F m \bar{3} m$ ThH $_{10}$ $_{10}$ with a dip structure in their DOS around $E_F$ $E_{F}$ . Our calculated $T_c$ $T_{c}$ values (225–235 K for CaH $_{6}$ $_{6}$ at 200 GPa and 156–158 K for ThH $_{10}$ $_{10}$ at 170 GPa) are quantitatively consistent with the experimental results. Remarkably, our results from the self-consistent treatment of the electron Green’s function contrasts with those cases with a peak structure in the DOS. This finding unifies the understanding of how DOS structures influence the evaluation of $T_c$ $T_{c}$ .

Superconductivity in CaH\(_{6}\) and ThH\(_{10}\) through fully ab initio Eliashberg method and self-consistent Green’s function

摘要