High Tc superconductivity in layered hydrides XH15 (X = Ca, Sr, Y, La) under high pressures

The theoretical predictions and experimental synthesis of H3S and LaH10 superconductors with record high superconducting transition temperatures (T-c) have promoted the hydrogen-based superconducors to be a research hotspot in the field of solid-state physics. Here, we predict an unprecedented layered structure CaH15, with high T-c of 189 K at 200 GPa using ab initio calculations. As concerns the novel structure, one layer is made of a hydrogen nonagon, the other layer consists of a Ca atom and six H-2 molecular units surrounding the Ca atom. This layered structure was also found in SrH15, YH15, and LaH15 at high pressures, each materials exhibit high T-c especially YH15 can reach above 200 K at 220 GPa. It represents the second class of layered superhydrides with high value of T-c after pentagraphene like HfH10.

Automated summary

Theoretical predictions and experimental synthesis have shown that H3S and LaH10 superconductors have record high superconducting transition temperatures, making hydrogen-based superconductors a hot topic in the field of solid-state physics. In this study, a new layered structure called CaH15 with high Tc of 189 K at 200 GPa is predicted using ab initio calculations. Similar layered structures were also found in SrH15, YH15, and LaH15 at high pressures, with each material exhibiting high Tc values.