Ab initio investigations of phonons and superconductivity in the cubic Laves structures LaAl2 and YAl2
Ab initio investigations of phonons and superconductivity in the cubic Laves structures LaAl2 and YAl2
复制标题
立方 Laves 结构 LaAl2 和 YAl2 中声子和超导性的从头算研究
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
H. M. Tütüncü
中科院分区：
文献类型：
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作者：
S. Duman;H. M. Tütüncü
我们对立方Laves结构LaAl2和YAl2的结构、弹性、电子、晶格动力学和电子-声子相互作用性质进行了从头算研究。计算是在密度泛函理论和线性响应形式下用赝势和平面波基进行的。计算的两种材料的声子色散关系与主对称方向的实验数据符合得很好。测得YAl_2和LaAl_2的平均电声耦合常数λ分别为0.35和0.65。因此，我们的结果表明，YAl_2的超导转变温度很低，而LaAl_2的超导转变温度T_c约为3 K，μ* = 为0.16。最后，我们观察到与La原子振动有关的软声子模在LaAl2超导电性中起主导作用。
We have performed an ab initio study of structural, elastic, electronic, lattice-dynamical, and electron-phonon interaction properties of the cubic Laves structures LaAl2 and YAl2. The calculations have been carried out within the density-functional theory and linear response formalism using pseudopotentials and a plane-wave basis. The calculated phonon dispersion relations for both materials accord very well with experimental data available for the principal symmetry directions. The average electron-phonon coupling constant λ is found to be 0.35 for YAl2 and 0.65 for LaAl2. Thus, our results indicate the superconducting transition temperature is very low for YAl2 but a superconducting transition temperature Tc of around 3 K for LaAl2 is found with μ* = 0.16. Finally, we have observed that the soft phonon modes related to the vibrations of La atoms play a dominant role in the superconductivity of LaAl2.