Unveiling the influence of the boron clathrate lattice on superconductivity in a ternary Mg–La–B system

Abstract

The clathrate lattice plays a crucial role in determining the properties of materials, specifically concerning the high superconductivity in high-pressure superhydrides. This study focuses on elucidating the influence of the boron clathrate lattice on superconductivity within the ternary Mg–La–B system. Using the structure prediction method and first-principles calculations, we have successfully identified a series of low-energy metallic Mg–La–B compounds at pressures of 0 and 50 GPa. Employing a rapid screening technique involving frozen-phonon calculations for electron–phonon coupling (EPC), we have singled out MgLaB₁₀ as a promising superconductor due to its largest EPC constant at the Brillouin zone center among all low-energy compounds. Subsequent EPC calculations covering the full Brillouin zone affirm the potential of MgLaB₁₀ as a superconductor with an estimated T_c of ∼20 K under ambient pressure. Interestingly, MgLaB₁₀ comprises B₁₈ and B₂₄ cages that encapsulate Mg and La atoms, respectively. Analysis shows that the coupling between σ-bonding electrons at the Fermi level and boron-associated phonon modes induced potential superconductivity. This work reveals the important influence of the boron clathrate lattice on superconductivity within the Mg–La–B system.