ABSTRACT
Ab initio pseudopotential calculations have been conducted for the superconducting filled skutterudite compounds BaPtGe
, SrPt
Ge
, and ThPt
Ge
in order to explore the effect of spin–orbit interaction(SOI) by using the planewave pseudopotential method and the density functional theory. The electronic structure calculations suggest that the density of states at the Fermi level is dominated by Ge atom's p states, with the guest atoms (Ba, Sr, or Th) making very little or no contribution. However, when the SOI is included, the phonon frequencies of BaPt
Ge
and SrPt
Ge
are hardened, which in turn decreases the electron–phonon interaction. By integrating the Eliashberg spectral function
F(ω) with SOI included, the average electron–phonon coupling parameters are found to be 0.74 for BaPt
Ge
, 0.79 for SrPt
Ge
, and 0.69 for ThPt
Ge
. Using a reasonable value of
= 0.10 for the effective Coulomb repulsion parameter, the superconducting critical temperature is found to be 5.36 K for BaPt
Ge
, 5.43 K for SrPt
Ge
, and 4.45 K for ThPt
Ge
with SOI. These values are in excellent accordance with their reported experimental values of 5.35 K, 5.4 K and 4.62 K.
Acknowledgments
Some of the calculations for this project were carried out using the computing facilities on the Intel Nehalem (i7) cluster (ceres) in the School of Physics, University of Exeter, United Kingdom.
Disclosure statement
No potential conflict of interest was reported by the authors.