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arXiv · 0803.1044

Electronic, dynamical and superconducting properties of CaBeSi

C. Bersier·A. Floris·A. Sanna·G. Profeta·A. Continenza·E. K. U. Gross·S. Massidda
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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.

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C. Bersier, A. Floris, A. Sanna, G. Profeta, A. Continenza, E. K. U. Gross, S. Massidda. 2008-03-07. Electronic, dynamical and superconducting properties of CaBeSi. https://doi.org/10.1103/physrevb.79.104503

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