High-temperature superconductivity in clathrate thorium-doped hexahydrides A1−xThxH6 ( <mml:math xmlns:mml="…

The discovery of high-temperature superconductivity in hydrides provides a promising route to achieve the goal of room-temperature superconductivity, but the ultrahigh pressure required to be synthesized severely limits their application. The next challenge is to find novel hydrides with high T₂ at low pressure, even ambient pressure. Here, we propose a strategy that elements with little electronegativity, large atomic volume, and suitable valence electron number can be regarded as a candidate for reducing the stable pressure by summarizing the superconducting rules of the clathrate hexahydrides, and find that thorium is a good ``precompressor. '' Based on the above strategy, we doped thorium into clathrate hexahydrides with a H₂₄ cage, and designed a series of hydrides. They could be dynamically stable at moderate pressure, which is much lower than that of the well-known hexahydrides CaH₆. Remarkably, LaTh₃H₂₄, AcTh₃H₂₄, and YThH₁₂ exhibit excellent superconductivity with high T₂ of 198 K at 50 GPa, 201 K at 60 GPa, and 208 K at 60 GPa, respectively. This work suggests that thorium doping is an effective method for finding hydrides with high T₂ at moderate pressure, and successfully helps us design a series of interesting high-temperature superconducting hydrides.