Exploring the pressure and spin–orbit coupling effects in Pt ₃ Sn ₂ S ₂ : a kagome-type analog of Co ₃ Sn ₂ S ₂

We present a detailed theoretical study of Pt₃Sn₂S₂, a layered kagome-type material obtained by replacing Co with Pt in Co₃Sn₂S₂, a system extensively studied in <i>Nat. Commun.</i> (2020, <b>11</b>, 3985) and <i>Rev. Phys.</i> (2022, <b>8</b>, 100072), though the Pt-analog remains largely unexplored. Thermodynamic stability was confirmed <i>via</i> formation energy calculations, while mechanical stability was evaluated using the Voigt-Reuss-Hill (VRH) approximation and elastic stability conditions. Dynamical and thermal stability were validated through phonon dispersion and <i>ab initio</i> molecular dynamics simulations, with Pugh's criterion classifying the material as ductile. Spin-orbit coupling (SOC) induces band splitting, accompanied by a SOC-driven transition from non-relativistic band touching to relativistic band inversion. Under applied pressure, the coupling of spin and valley degrees of freedom generates spin-valley intertwined Dirac cones, enabling tunable electronic properties for spintronic and valleytronic applications. Furthermore, Boltzmann transport calculations using AMSET reveal a high Seebeck coefficient (80 μV K^-1 without SOC) at 300 K and low thermal conductivity, highlighting its potential for high-performance thermoelectric devices. Further impurity scattering (IMP) dominates at low temperatures (<200 K), and decreases with temperature, while polar optical phonon (POP) scattering becomes significant at higher temperatures, overtaking IMP near 250 K without spin-orbit coupling. With SOC, impurity scattering exhibits an anomalous increase with temperature, while POP is more active even at low temperatures. These findings establish Pt₃Sn₂S₂ as a promising material for applications spanning topological physics, thermoelectrics, and advanced electronic technologies.