Berlin 2008 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 36: Superconductivity: Properties, Electronic Structure, Order Parameter
TT 36.5: Talk
Friday, February 29, 2008, 11:15–11:30, H 0104
Electrons, phonons and superconducting properties of CaBeSi — •A. Floris1, C. Bersier1, A. Sanna1,2, G. Profeta3, A. Continenza3, E.K.U. Gross1, and S. Massidda2 — 1Institut für Theoretische Physik, Freie Universität Berlin, Germany — 2INFM SLACS and Dipartimento di Scienze Fisiche, Università degli Studi di Cagliari, Italy — 3C.A.S.T.I. - INFM and Dipartimento di Fisica, Università degli studi dell’Aquila, Italy
We present first-principles calculations on the normal and superconducting state of CaBexSi2−x (x=1)[1,2], in the framework of the density functional theory for superconductors (SCDFT)[3,4] . 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. Although our calculations show that CaBeSi has a low critical temperature (Tc ≈0.6 K), it exhibits a complex gap structure, with three gaps at the Fermi level. Besides the two σ and π 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 π states.
[1] N. May et al., Z. Naturforsh. B 2, 1947 (1977).
[2] F. Sano et al., CP850 Low Temperature Physics: 24th International Conference on Low Temperature Physics, 2006.
[3] M. Lüders et al., Phys. Rev. B, 72, 024545 (2005).
[4] M. A. L. Marques et al., Phys. Rev. B, 72, 024546 (2005).