Multiband nature of room-temperature superconductivity in LaH10 at high pressure

Recently, the discovery of room-temperature superconductivity (SC) was experimentally realized in the fcc phase of LaH io under megabar pressures. This SC of compressed LaH10 has been explained in terms of strong electron-phonon coupling (EPC), but the detailed nature of how the large EPC constant and high superconducting transition temperature T-c are attained has not yet been clearly identified. Based on the density-functional theory and the Migdal-Eliashberg formalism, we reveal the presence of two nodeless, anisotropic superconducting gaps on the Fermi surface (FS). Here, the small gap is mostly associated with the hybridized states of H s and La f orbitals on the three outer FS sheets, while the large gap arises mainly from the hybridized state of neighboring H s or p orbitals on the one inner FS sheet. Further, we find that compressed YH10 with the same sodalitelike clathrate structure has the two additional FS sheets, enhancing EPC constant and T-c. It is thus demonstrated that the nature of room-temperature SC in compressed LaH10 and YH10 features the multiband pairing of hybridized electronic states with large EPC constants.