Strong-coupling superconductivity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>LiB</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">C</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math> trilayer films
Miao Gao, Xun-Wang Yan, Zhong-Yi Lu, Tao Xiang
Abstract
Coupling between $\ensuremath{\sigma}$-bonding electrons and phonons is generally very strong. To metallize $\ensuremath{\sigma}$ electrons provides a promising route to hunt for new high-${T}_{c}$ superconductors. Based on this picture and first-principles density functional calculation with Wannier interpolation for electronic structure and lattice dynamics, we predict that trilayer film ${\mathrm{LiB}}_{2}{\mathrm{C}}_{2}$ is a good candidate to realize this kind of high-${T}_{c}$ superconductivity. By solving the anisotropic Eliashberg equations, we find that free-standing trilayer ${\mathrm{LiB}}_{2}{\mathrm{C}}_{2}$ is a phonon-mediated superconductor with ${T}_{c}$ exceeding the liquid-nitrogen temperature at ambient pressure. The transition temperature can be further raised to 125 K by applying a biaxial tensile strain.