Ab initio study of Li-Mg-B superconductors

LiB, a predicted layered compound analogous to the MgB$_2$ superconductor,\nhas been recently synthesized via cold compression and quenched to ambient\npressure, yet its superconducting properties have not been measured. According\nto prior isotropic superconductivity calculations, the critical temperature\n($T_{\\rm{c}}$) was expected to be only 10$-$15 K. Using the anisotropic\nMigdal-Eliashberg formalism, we show that the $T_{\\rm{c}}$ may actually exceed\n32 K. Our analysis of the contribution from different electronic states helps\nexplain the detrimental effect of pressure and doping on the compound's\nsuperconducting properties. In the search for related superconductors, we\nscreened Li-Mg-B binary and ternary layered materials and found metastable\nphases with $T_{\\rm{c}}$ close to or even 10$-$20% above the record 39 K value\nin MgB$_2$. Our reexamination of the Li-B binary phase stability reveals a\npossible route to synthesize the LiB superconductor at lower pressures readily\nachievable in multianvil cells.\n