β型烧绿石结构氧化物超导体AOs_2O_6(A=K,Rb,Cs)电子能带结构的第一性原理计算

First-principles calculations on the electronic band structure of β-Pyrochlore superconductors AOs_2O_6(A=K,Rb,Cs)

用全势线性缀加平面波方法计算β型烧绿石结构氧化物超导体AOs2O6(A=K,Rb,Cs)的电子能带结构及态密度.计算发现电子自旋轨道耦合和在位库仑势U的作用增大了费米面处态密度值.通过计算还得到这三种化合物电子关联常数λc分别为1.55,1.12和0.73.由实验测量与能带计算得到的电子比热容系数的比值得到电子质量提高参数.通过分析这三种化合物电子质量提高参数,推算出它们的电声子耦合常数λep分别为1.56,0.78和1.08.由此提出KOs2O6为强电子关联和强电声子耦合系统,而RbOs2O6和CsOs2O6的电子关联性与电声子耦合为中等.

Using the full-potential linearized augmented plane wave method, we studied the electronic energy band structures of β- pyrochlore superconductors AOs2O6（A = K, Rb, Cs）. The values of electronic density of states at the Fermi level have been significant enhanced for the three compounds due to taking to consideration of the spin-orbit coupling and the on-site Coulomb interactions. The electronic Coulomb correlation constants λc = 1.55, 1.12 and 0.73 were obtained. Analyzing the electronic mass enhancement parameters obtained from the experimental data and the calculated electronic density of states, we deduced the electron-phonon coupling constants λep= 1.56, 0.78 and 1.08 for the three compounds, respectively. It is suggested that KOs2O6 is a strongly-correlated and strongly electron-phonon coupled system, while RbOs2O6 and CsOs2O6 are medium in these properties.