Prediction of high-temperature superconductivity in lithium-doped thorium superhydrides under high pressures

Abstract

Hydrogen-rich compounds with distinct hydrogenic frameworks have recently emerged as promising candidates for high-temperature superconductivity. In this work, we systematically investigate the high-pressure phase diagram of Li-Th-H system at 300 GPa using advanced first-principles structure prediction method. A thermodynamically stable phase, Li 2 ThH 17 , containing intriguing H 28 and H 20 cages, is identified with a superconducting critical temperature, T c , of 162 K at 300 GPa. This high-temperature value significantly exceeds that of the isostructural rare-earth hydrides under the same pressure conditions. The enhancement is primarily attributed to an additional electron-phonon coupling contribution originating from the strong interaction between the high Th f and hydrogen electronic density of states near the Fermi level and medium-to low-frequency phonon modes of the metal sublattice. Moreover, effective hole doping in the isostructural Li 2 ThH 16 increases the T c to 194 K. These results offer valuable insights into the superconducting properties of actinide hydrides under extreme pressures.