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

Abstract

Recently, superconductivity in BaPtAs with the noncentrosymmetric SrPtSb and the centrosymmetric YPtAsstructure has been discovered. Its noncentrosymmetric and centrosymmetric structures make BaPtAs a charming compound for searching the effect of spin-orbit coupling (SOC) onto superconductors with broken and preserved spatial inversion symmetry. We have investigated the effect of SOC on the physical and electron-phonon interaction properties of these phases of BaPtAs by using the generalized gradient approximation of the density functional theory and the plane-wave pseudopotential method. The inclusion of SOC has moderate effect on the elastic and electronic properties, and on phonon frequencies for both phases of BaPtAs. However, SOC makes an opposite impact on their Eliashberg spectral function. For the noncentrosymmetric phase, this coupling decreases the strength of dominant peaks of Eliashberg spectral function, reducing the values of average electron-phonon coupling and superconducting transition temperature. The scenario is exactly opposite for the centrosymmetric phase. For both phases, the hybridized Pt-As vibrations play a strongly significant role in determining their electron-phonon interaction properties since their electronic states have the dominant contribution near the Fermi level. The superconducting temperature is estimated to be 2.87 K for the SrPtSb phase and 2.38 K for the YPtAs phase. These values compare well with the reported measured values of 2.8 K and 2.1-3.0 K, respectively.

The Influence of Spin‐Orbit Interaction on the Electron‐Phonon Coupling in Tl‐Rich Cubic AuCu3‐Type Superconductors: Comparison with La3Tl

“…This result is expected because including this coupling makes our calculations more physical. It is worth mentioning that a similar observation has been made by previous ab initio calculations [ 49–55 ] for other superconductors containing heavy elements. Finally, we believe that the good agreement between the calculated and experimental $$T_{\text{c}}$$ values validates the trustworthiness of our LDA + SOC calculations.…”

“…Since all the studied compounds in our calculations include the Tl element, our calculations have been realized by the LDA + SOC method rather than the LDA + U one. Furthermore, previousab initio calculations [ 49–55 ] show that the inclusion of SOC is enough to explain the physical and superconducting properties of superconductors with heavy elements. The previous ab initio calculations indicate the validity of our present calculations.…”

Electronic, phononic and superconducting properties of trigonal Li2 MSi2 (M = Ir, Rh)

“…The lattice parameters a, c, and the Ir-Si and Rh-Si bond lengths are listed for two compounds in table 1 along with available experimental values. Additionally, the values of bulk modulus (B) and its pressure derivative (B ) are calculated by minimizing the crystal total energy for different values of the crystal volume by means of the Murnaghan equation of state [46][47][48]. They are calculated for both compounds as listed in table 1 The band shapes are similar for both compounds.…”

“…The inclusion of SOC is effective along the high symmetry points due to the centrosymmetric structure. Recently, theoretical study done by Tütüncü et al [47] was about hexagonal BaPtAs with noncentrosymmetric SrPtSb-type and centrosymmetric YPtAs-type crystal structures. In their study, the effect of spin-orbit coupling on superconductivity was considered with broken and preserved spatial inversion symmetries and reported splitting the bands for both structures.…”

“…All calculated values in table 3 are weakly effected by the inclusion of SOC. In addition to the mechanical properties, it is well known that the Debye temperature (Θ D ) is an important fundamental parameter for a comprehensive understanding of the thermodynamics properties or behaviors such as thermal conductivity, specific heat, elastic constants, and superconductivity [47,63,64]. In the experimental studies, the normal-state specific heat measurements are used to estimate the Debye temperature (Θ D ).…”