Theoretical investigation of superconductivity in SrAuSi3 and SrAu2Si2

Abstract

The structural and electronic properties of BaNiSn 3 -type SrAuSi 3 and ThCr 2 Si 2 -type SrAu 2 Si 2 have been investigated by using the planewave pseudopotential method and the density functional theory. The electronic structures and phonon dispersion relations of these two materials have been analyzed with and without the inclusion of spin-orbit interaction, and similarities and differences highlighted. By integrating the Eliashberg spectral function α 2 F(ω), the average electron-phonon coupling parameter is determined to be λ = 0.47 for SrAuSi 3 and 0.42 for SrAu 2 Si 2 . The largest contribution to the electron-phonon coupling for SrAuSi 3 comes from the Si p electrons near the Fermi energy and Si-related vibrations. Using a reasonable value of µ * = 0.12 for the effective Coulomb repulsion parameter, the superconducting critical temperature T c for SrAuSi 3 is found to be 1.47 K which compares very well with its experimental value of 1.54 K.

Physical properties of hexagonal BaPtAs with noncentrosymmetric SrPtSb-type and centrosymmetric YPtAs-type crystal structures: Effects of spin-orbit coupling

“…Recently, the linear response approach and the Migdal-Eliashbergh approach [31][32][33][34] have been combined to probe electron-phonon interaction properties of several BaNiSn 3 -type NCS such as SrAuSi 3 , CaIrSi 3 , LaIrSi 3 , LaPdSi 3 , LaRhSi 3 , and LaPtSi 3 . The results of these theoretical studies [31][32][33][34] reveal that the impact of SOC on the electron-phonon interaction in these NCSs is little due to the weak effect of this coupling on their electronic band structures near the Fermi level. Furthermore, first-principles pseudopotential calculations [35] have been carried out to investigate the effect of SOC on superconductivity in the noncentrosymmetric BaPtSb superconductor.…”

The effect of spin orbit interaction on the physical properties of LaTSi3 (T = Ir, Pd, and Rh): First-principles calculations

“…These theoretical works are not complete enough to explain the origin of superconductivity in these NCS because their phonon properties must be calculated to study electron-phonon interaction. This reality motivated Arslan et al 34 to study the electron-phonon interaction in SrAuSi 3 . This work has been done with and without spin-orbit interactions.…”

Microscopic investigation of the weakly correlated noncentrosymmetric superconductor SrAuSi3

“…Single-band fully-gapped BCS superconductivity and weak electronic correlation confirm the small splitting of the bands in the vicinity of the Fermi level E F , visible only in proximity of the Brillouin zone edges. 8 This hints at a small ASOC that, along with weak correlations, may hinder the singlet-triplet mixing. Although a mixed-parity pairing is predicted to be a general feature of NCSs with ASOC, many weakly correlated compounds exhibit a rather simple behavior, 3 as reported here for the SrAuSi 3 case.…”