First Principles Search for New Superconducting Layered Borides

The identification of novel crystal structures is a fundamental step for predicting new stable compounds in alloys. While performing ab initio data mining of intermetallic compounds [1], we discover a new family of layered metal borides [2], of which MgB$_{2}$ is one particular element (the new phases are called Metal Sandwich (MS)). Thermodynamic stability and electronic properties of these MS phases are investigated in details, leading to the prediction of a hypothetical novel superconductor MS-LiB [2,3]. Calculations show that the MS phases in the Li-B system exhibit electronic features similar to those of MgB$_{2}$ [2,3] and CaC$_{6}$ [4]. Although the predicted critical temperature of LiB is lower than that of MgB$_{2}$ (references [4] and [5] for MS2-LiB and MS1-LiB, respectively), the peculiarities of MS-LiB in terms of electronic structure, layer arrangements and doping capabilities allow a lot of freedom in the search for higher T$_{c}$ systems [5,6]. We acknowledge the Teragrid-Partnership for computational resources. Research supported by ONR and NSF. [1] Phys. Rev. Lett. \textbf{9}1, 135503 (2003). [2] Phys. Rev. B \textbf{73}, 180501(R) (2006). [3] Phys. Rev. B \textbf{74}, 224507 (2006). [4] Phys. Rev. B \textbf{75}, 064510 (2007). [5] Phys. Rev. B \textbf{75}, 144506 (2007). [6] A. N. Kolmogorov, M. Calandra, and S. Curtarolo, \textit{Engineering superconductors with ab initio methods: ternary metal borides}, (2007).