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TT: Fachverband Tiefe Temperaturen

TT 18: Superconductivity: Poster

TT 18.21: Poster

Monday, March 18, 2024, 15:00–18:00, Poster C

Prediction of high-T_c superconductivity in ternary actinium beryllium hydrides at low pressure — •kun gao — ZGH, RUB, Bochum, Germany

Hydrogen-rich superconductors are promising candidates to achieve room-temperature superconductivity. However, the extreme pressures needed to stabilize these structures significantly limit their practical applications. An effective strategy to reduce the external pressure is to add a light element M that binds with H to form MH x units, acting as a chemical precompressor. We exemplify this idea by performing ab initio calculations of the Ac-Be-H phase diagram, proving that the metallization pressure of Ac-H binaries, for which critical temperatures as high as 200 K were predicted at 200 GPa, can be significantly reduced via beryllium incorporation. We identify three thermodynamically stable (AcBe₂H₁₀, AcBeH₈, and AcBe₂H₁₄) and four metastable compounds (fcc AcBeH₈, AcBeH₁₀, AcBeH₁₂ and AcBe₂H₁₆). All of them are superconductors. In particular,fcc AcBeH₈ remains dynamically stable down to 10 GPa, where it exhibits a superconducting-transition temperature T_c of 181 K. The Be-H bonds are responsible for the exceptional properties of these ternary compounds and allow them to remain dynamically stable close to ambient pressure. Our results suggest that high-Tc superconductivity in hydrides is achievable at low pressure and may stimulate experimental synthesis of ternary hydrides.

Keywords: High pressure physics; High-Tc superconductivity; Hydrogen-rich superconductive hydries