Lifshitz transition in ThFeAsN superconductor at high pressure
Smritijit Sen1*, Guang-Yu Guo1,2
1Department of Physics and Center for Theoretical Physics, National Taiwan University, Taipei, Taiwan
2Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan
* Presenter:Smritijit Sen,
Pressure dependent structural parameters and electronic structure of ThFeAsN superconductor are studied through first principles density functional theory [1]. No anomalies in the structural parameters as well as elastic constants with pressure indicate that there is no structural transition in ThFeAsN with pressure which is consistent with the experiments. Density of states, band structure and Fermi surface as a function of hydrostatic pressure has been thoroughly investigated. Density of states at the Fermi level, coming from Fe-d orbitals follows the same trend as that of the superconducting transition temperature (Tc) as a function of hydrostatic pressure. We also observed a pressure induced orbital selective Lifshitz transition in ThFeAsN compound which is quite different from the Lifshitz transitions observed in the other families of Fe-based superconductor. Pressure dependent modification of Fermi surface topology at higher pressure, is largely responsible for the reduction of superconducting Tc in ThFeAsN superconductor. Spin-orbit coupling does not affect the Lifshitz transition but it modifies the energy ordering of bands near Γ point at higher pressure.

[1] Smritijit Sen and Guang-Yu Guo, Phys. Rev. Materials 4, 104802 (2020).

Keywords: Fe based Superconductor, Lifshitz transition, First principles calculation