Superconductivity in compressed ternary alkaline boron hydrides

Recently, the carbonaceous sulfur hydride was synthesized [E. Snider et al., Nature (London) 586, 373 (2020)], and the measured superconducting transition temperature (T-c) is about 278 K under 267 GPa, placing it as a promising candidate of the room temperature superconductor. However, the ultrahigh synthesis pressure is indeed a challenge for experimental technique, stimulating us to search other high temperature superconductors under relatively low pressure. Here we perform comprehensively structural searches of ternary alkaline (Am) boron hydrides. Our calculations indicate that the ternary AmB2H8 hydrides are energetically stable at about 10 GPa. Interestingly, the metallic Rb/CsB2H8 polyhydrides are superior superconductors with high T-c of similar to 100 K at 25 GPa. The electron-phonon coupling calculations suggest that the Am atoms are promising electron contributors, which effectively improve the T-c and decrease the synthesized pressure in complex hydrides. These findings elucidate the superconductivity mechanism of AmB2H8 hydrides and offer crucial insights for design and synthesis of novel superconductors.

Automated summary

Recently, researchers synthesized carbonaceous sulfur hydride and found that it exhibits a high superconducting transition temperature under ultra-high pressure, making it a promising candidate for room temperature superconductivity. In order to search for more high-temperature superconductors under relatively low pressure, the researchers conducted structural searches and discovered that ternary alkaline boron hydrides exhibit thermodynamic stability at around 10 GPa. Additionally, metallic polyhydrides also exhibit excellent superconducting properties, offering crucial insights for the design and synthesis of novel superconductors.