Electronic, dynamical and superconducting properties of CaBeSi

Abstract

We report first-principles calculations on the normal and superconducting state of CaBe(x)Si(2-x) (x=1), in the framework of density functional theory for superconductors (SCDFT). CaBeSi is isostructural and isoelectronic to MgB2 and this makes possible a direct comparison of the electronic and vibrational properties and the electron-phonon interaction of the two materials. Despite the many similarities with MgB2 (e.g. sigma bands at the Fermi level and a larger Fermi surface nesting), according to our calculations CaBeSi has a very low critical temperature (Tc ~ 0.4 K, consistent with the experiment). CaBeSi exhibits a complex gap structure, with three gaps at Fermi level: besides the two sigma and pi gaps, present also in MgB2, the appearance of a third gap is related to the anisotropy of the Coulomb repulsion, acting in different way on the bonding and antibonding electronic pi states.

6 pages, 5 figures

References in corpus (6)

• Superconductivity in the Intercalated Graphite Compounds C6Yb and C6Ca
• Superconductivity of bulk CaC6
• Ab-initio theory of superconductivity - I: Density functional formalism and approximate functionals
• Ab-initio theory of superconductivity - II: Applications to elemental metals
• Superconductivity in lithium, potassium and aluminium under extreme pressure: A first-principles study
• Electrons and phonons in the ternary alloy CaAl${}_{2-x}$Si${}_x$} as a function of composition

Cited by in corpus (12)

• Electron-phonon interactions from first principles
• Evolution of multi-gap superconductivity in the atomically thin limit: Strain-enhanced three-gap superconductivity in monolayer MgB${}_2$
• High-temperature Superconductivity in Layered Nitrides β-Li${}_x$MNCl (M = Ti, Zr, Hf): Insights from Density-functional Theory for Superconductors
• Superconducting pairing mediated by spin-fluctuations from first principles
• Density Functional Theory for Plasmon-Assisted Superconductivity
• Density Functional Theory for Superconductors with Particle-hole Asymmetric Electronic Structure
• Superconductivity of $\beta$-Gallium
• Multiband superconductivity in Pb, H under pressure and CaBeSi from {\it ab-initio} calculations
• Electron-phonon superconductivity in C-doped topological nodal-line semimetal Zr${}_5$Pt${}_3$: A muon spin rotation and relaxation ($\mu$SR) study
• Basic variables to be reproduced in the first-principles theory for superconductors: Fluctuation of the particle number
• Exploring Superconductivity in Ba${}_3$Ir${}_4$Ge${}_{16}$: Experimental and Theoretical Insights
• Probing the superconducting gap structure of ScRuSi via $\mu$SR and first-principles calculations