High-Temperature Superconductivity in a Th–H System under Pressure Conditions

New stable phase thorium decahydride Fm3̅ m-ThH₁₀, a high-temperature superconductor with T_C up to 241 K (-32 °C), critical field H_C up to 71 T, and superconducting gap Δ₀ of 52 meV at 80-100 GPa, is predicted by evolutionary algorithm USPEX. Another phase, P2₁/ c-ThH₇, is found to be a superconductor with T_C of 62 K. Analysis of the superconducting state was performed within Eliashberg formalism, and H_C( T), Δ( T), and T_C( P) functions with a jump in the specific heat at critical temperature were calculated. Several other new thorium hydrides were predicted to be stable under pressure, including ThH₃, Th₃H₁₀, ThH₄, and ThH₆. Thorium (which has s² d² electronic configuration) forms high- T_C polyhydrides similar to those formed by s² d¹ metals (Y-La-Ac). Thorium belongs to the Mg-Ca-Sc-Y-La-Ac family of elements forming high- T_C superconducting hydrides.