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arXiv 2407.09347cond-mat.supr-con
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常压 Mg$_x$B$_2$C$_2$ 和 Na$_x$BC 超导体的第一性原理设计

First-principles design of ambient-pressure Mg$_x$B$_2$C$_2$ and Na$_x$BC superconductors

Charlsey R. Tomassetti, Daviti Gochitashvili, Christopher Renskers, Elena R. Margine, Aleksey N. Kolmogorov

AI总结:

本文通过第一性原理相图与 Migdal-Eliashberg 方程,设计出常压下临界温度可达 43-84 K 的 Mg$_x$B$_2$C$_2$ 和 Na$_x$BC 超导体,并揭示 BC 层屈曲对超导性的抑制作用。

摘要:

我们采用从头算建模方法,研究在基于已知 MgB$_2$C$_2$ 和最近提出的热力学稳定 NaBC 三元化合物的常压材料中实现高温常规超导的可能性。所构建的 $(T,P_M)$ 相图(M = Mg 或 Na)表明,这些层状金属硼碳化物可以通过热脱插层进行空穴掺杂,该方法已在先前实验中成功用于制备 Li$_y$BC($y=1>x\gtrsim0.5$)样品。触发 NaBC 脱钠所需的相对较低温度阈值可能有助于防止缺陷的形成,而最近的研究表明这些缺陷对脱锂 LiBC 类似物中的电子-声子耦合有害。根据我们对各向异性全带宽 Migdal-Eliashberg 方程的数值求解,所提出的 Mg$_x$B$_2$C$_2$ 和 Na$_x$BC 材料表现出 43 K 至 84 K 之间的超导临界温度。同时,我们证明,在重掺杂 Na$_x$BC 化合物中有利的无缺陷蜂窝状 BC 层屈曲,可以显著降低或有效抑制这些材料实现 MgB$_2$ 型超导的潜力。

英文摘要:

We employ ab initio modeling to investigate the possibility of attaining high-temperature conventional superconductivity in ambient-pressure materials based on the known MgB$_2$C$_2$ and recently proposed thermodynamically stable NaBC ternary compounds. The constructed $(T,P_M)$ phase diagrams (M = Mg or Na) indicate that these layered metal borocarbides can be hole-doped via thermal deintercalation that has been successfully used in previous experiments to produce Li$_y$BC ($y=1>x\gtrsim0.5$) samples. The relatively low temperature threshold required to trigger NaBC desodiation may help prevent the formation of defects shown recently to be detrimental to the electron-phonon coupling in the delithiated LiBC analog. According to our numerical solutions of the anisotropic full-bandwidth Migdal-Eliashberg equations, the proposed Mg$_x$B$_2$C$_2$ and Na$_x$BC materials exhibit superconducting critical temperatures between 43 K and 84 K. At the same time, we demonstrate that buckling of defect-free honeycomb BC layers, favored in heavily-doped Na$_x$BC compounds, can substantially reduce or effectively suppress the materials' potential for MgB$_2$-type superconductivity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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