Superconductivity in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Li</mml:mi><mml:mn>8</mml:mn></mml:msub><mml:mi>Au</mml:mi></mml:mrow></mml:math> electride
Xiaohua Zhang, Yansun Yao, Shicong Ding, Aitor Bergara, Fei Li, Yong Liu, Xiang‐Feng Zhou, Guochun Yang
Abstract
Located at crystal voids, interstitial anion electrons (IAEs) have diverse topologies, which may be tuned to achieve different properties. Elucidating the role of IAEs in electron-phonon coupling (EPC), and using it to design electride superconductors, leads to the current prediction of superconducting ${\mathrm{Li}}_{8}\mathrm{Au}$ at high pressure. We suggest that the occurence of high-temperature superconductivity in electrides requires high-symmetry structures with hydrogenlike cages, an electron acceptor element to balance charges, and isolated IAEs coupled with medium-frequency vibrations. The uniquely designed ${\mathrm{Li}}_{8}\mathrm{Au}$ electride has a NaCl-type ($B1$) lattice, with atomic Au and cubic ${\mathrm{Li}}_{8}$ cages as bases. Isolated IAEs are formed at the cage centers, with extra charges taken up by Au. These octahedrally coordinated IAEs have a $p$-orbital-like attribute and are strongly coupled with atomic vibrations in the ${\mathrm{Li}}_{8}$ cages. The strong EPC in ${\mathrm{Li}}_{8}\mathrm{Au}$ results in a calculated ${T}_{c}$ of 73.1 K at 250 GPa, which is the highest ${T}_{c}$ reported to date for all the electrides. A slight substitutional Pt doping can enhance the ${T}_{c}$ of ${\mathrm{Li}}_{8}\mathrm{Au}$ to exceed liquid nitrogen temperature.