Theoretical investigation of antisymmetric spin-orbit coupling effect on the physical properties of noncentrosymmetric BaPtSb superconductor

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First principles pseudopotential calculations have been performed to explore the effect of spin-orbit coupling on the electronic, elastic, mechanical, vibrational and electron-phonon interaction properties of noncentrosymmetric BaPtSb crystallizing in the hexagonal SrPtSb-type. This coupling makes only moderate changes to the elastic and mechanical properties but significant changes to the phonon spectrum in the acoustic range. Analysis of the Eliashberg spectral function reveals that these low-frequency phonon modes originate from the vibrations of Pt and Sb atoms and couple strongly to their d and p electronic states at the Fermi level. The spin-orbit coupling has a significant effect on the electron-phonon interaction properties by decreasing the frequencies of some phonon modes and increasing the strength of the most dominant peak of the Eliashberg spectral function. The average electron-phonon coupling increases from 0.617 without spin-orbit coupling to 0.629 with spin-orbit coupling, resulting in the corresponding changes to the superconducting transition temperature from 1.46 to 1.54 K. The latter value of superconducting transition temperature compares very well with its experimental value of 1.64 K.