Electronic, vibrational, and superconducting properties of CaBeSi: First-principles calculations

被引：31

作者：

Bersier, C. ^{[1
]}

Floris, A. ^{[1
]}

Sanna, A. ^{[1
,2
,3
]}

Profeta, G. ^{[4
]}

Continenza, A. ^{[4
]}

Gross, E. K. U. ^{[1
]}

Massidda, S. ^{[2
,3
]}

机构：

[1] Free Univ Berlin, Inst Theoret Phys, D-14195 Berlin, Germany

[2] Univ Cagliari, Dept Phys, I-09024 Monserrato, Ca, Italy

[3] Sardinian Lab Computat Mat Sci SLACS INFM CNR, I-09024 Monserrato, Ca, Italy

[4] Univ Aquila, Dipartimento Fis, CNISM, I-67010 Laquila, Italy

来源：

PHYSICAL REVIEW B | 2009年 / 79卷 / 10期

基金：

瑞士国家科学基金会;

关键词：

beryllium alloys; boron alloys; calcium alloys; density functional theory; electronic density of states; electron-phonon interactions; Fermi level; magnesium alloys; silicon alloys; superconducting materials; superconducting transition temperature; vibrational modes; MGB2; PSEUDOPOTENTIALS; APPROXIMATION;

D O I：

10.1103/PhysRevB.79.104503

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We report first-principles calculations on the normal and superconducting state of CaBexSi2-x (x=1), in the framework of density-functional theory for superconductors. 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 many similarities with MgB2 (e.g., sigma and pi bands at the Fermi level and an even larger density of states), according to our calculations CaBeSi has a very low critical temperature T-c approximate to 0.4 K consistent with the experiment. CaBeSi exhibits a complex gap structure, with three gaps at the Fermi level: besides the 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 ways on the bonding and antibonding electronic pi states.

引用

页数：7

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