First-principles design of ambient-pressure MgBC and NaBC superconductors
arXiv:2407.09347 · doi:10.1103/PhysRevMaterials.8.114801
Abstract
We employ ab initio modeling to investigate the possibility of attaining high-temperature conventional superconductivity in ambient-pressure materials based on the known MgBC and recently proposed thermodynamically stable NaBC ternary compounds. The constructed 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 LiBC () 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 MgBC and NaBC 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 NaBC compounds, can substantially reduce or effectively suppress the materials' potential for MgB-type superconductivity.
11 pages, 8 figures and 1 table
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