发现常压下超导转变温度达140K的新型氢化物材料
High-temperature superconductivity in Li$_2$AuH$_6$ mediated by strong electron-phonon coupling under ambient pressure
- 通过人工智能搜索发现Li₂AuH₆具有强电子-声子耦合
- 常压下理论超导转变温度高达约140K
- 强调声子模式对高临界温度超导的重要性，适合材料设计者参考
我们利用自主开发的AI搜索引擎（InvDesFlow）系统研究了常压稳定超导氢化物。发现一种具有金-氢八面体结构的立方相Li₂AuH₆是潜在候选材料。经热力学分析，提出可通过已知的LiAu和LiH化合物在常压下可行合成该材料。第一性原理计算表明，Li₂AuH₆在常压下具有约140 K的高超导转变温度。其中，氢1s电子与金-氢八面体振动模式以及锂原子振动模式均表现出强烈的电子-声子耦合，而后者在以往类似研究中未被重视。因此，不同于以往通过寻找金属共价键来发现高Tc超导体的做法，本文强调强电子-声子耦合的声子模式的重要性，并建议可通过向二元或三元氢化物中掺杂原子引入更多具有强电子-声子耦合的声子模式，这是在多组分化合物中寻找高Tc超导体的有效途径。
原文摘要 · Abstract (English)
We used our developed AI search engine~(InvDesFlow) to perform extensive investigations regarding ambient stable superconducting hydrides. A cubic structure Li$_2$AuH$_6$ with Au-H octahedral motifs is identified to be a candidate. After performing thermodynamical analysis, we provide a feasible route to experimentally synthesize this material via the known LiAu and LiH compounds under ambient pressure. The further first-principles calculations suggest that Li$_2$AuH$_6$ shows a high superconducting transition temperature ($T_c$) $\sim$ 140 K under ambient pressure. The H-1$s$ electrons strongly couple with phonon modes of vibrations of Au-H octahedrons as well as vibrations of Li atoms, where the latter is not taken seriously in other previously similar cases. Hence, different from previous claims of searching metallic covalent bonds to find high-$T_c$ superconductors, we emphasize here the importance of those phonon modes with strong electron-phonon coupling (EPC). And we suggest that one can intercalate atoms into binary or ternary hydrides to introduce more potential phonon modes with strong EPC, which is an effective approach to find high-$T_c$ superconductors within multicomponent compounds.
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