[16p-D209-1~14] 11.1 Fundamental properties

▲ [16p-D209-13] (La,Th)H₁₀: the potential high-Tc superconductors stabilized thermodynamically below 200 GPa

〇HOU SOU¹, Kenta Hongo², Ryo Maezono¹ (1.Inf. Sci. JAIST, 2.RCACI. JAIST)

Keywords:superconductor, electron-phonon coupling, superconducting hydride

The recent high-pressure experimental discovery of superconductivity in (La,Y)H₁₀, (La,Ce)H₉, (La,Ce)H₁₀, (Y,Ce)H₉, and (La,Nd)H₁₀ shows that the ternary rare-earth clathrate hydride can be a promising candidate for high-temperature superconductor. In this work, we theoretically demonstrate that the combination of actinide-metal thorium (Th) and rare-earth-metal lanthanum (La) with hydrogen can also form some ternary hydrides with cage-like structures to be stable at 200 GPa. Using the evolutionary algorithms combined with the first-principles calculations, we have predicted the pressure-dependent ternary phase diagram of La_xTh_yH_z. Our calculations show that the hydrogen-rich phases such as (La,Th)H₉ (only including P6m2-LaThH₁₈) and (La,Th)H₁₀ (including I4/mmm-La₃ThH₄₀, R3m-LaThH20, and I4/mmm-LaTh₃H₄₀) with H₂₉ and H₃₂ cages can be thermodynamically stable below 200 GPa. More importantly, the electron-phonon coupling (EPC) calculations show that the (La,Th)H₁₀ series could the potential superconductors, of which I4/mmm-La₃ThH₄₀ at 200 GPa exhibits the large EPC constant λ = 2.46 with a highest transition temperature (T_c) of 210 K. Since there are few previous studies on ternary hydrides composed of actinide metals, the present work would greatly stimulate the further discovery of this type of ternary hydrides and provide useful guidance for the high-pressure experimental studies on them. type of ternary hydrides and provide useful guidance for the high-pressure experimental studies on them.