Ionicity versus covalency in MgB2:: The hidden role of Mg

被引：12

作者：

Deng, S ^{[1
]}

Simon, A ^{[1
]}

Köhler, J ^{[1
]}

Bussmann-Holder, A ^{[1
]}

机构：

[1] Max Planck Inst Solid State Res, D-70569 Stuttgart, Germany

来源：

JOURNAL OF SUPERCONDUCTIVITY | 2003年 / 16卷 / 06期

关键词：

magnesium diboride; two gap superconductor band structure; chemical bonding;

D O I：

10.1023/A:1026266601746

中图分类号：

O59 [应用物理学];

学科分类号：

摘要：

The discovery of superconductivity in MgB2 at T-c = 39 K has initiated great efforts to identify its microscopic origin. A superconducting two-gap structure has been firmly established experimentally. However, the importance of the smaller gap which is essential in pushing T-c above the BCS value of a one-gap superconductor has mostly been ignored. Our results based on ab initio calculations and a newly introduced k, j-dependent bonding indicator show that Mg contributes significantly to states from which the small gap originates. In addition, it is revealed that Mg-B covalent bonding is an important factor in limiting the substitution of Mg in MgB2.

引用

页码：919 / 922

页数：4

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