paper

Ab initio downfolding study of the iron-based ladder superconductor BaFeS

arXiv:1507.05715 · doi:10.1103/PhysRevB.92.054515

Abstract

Motivated by the recent discovery of superconductivity in the iron-based ladder compound BaFeS under high pressure, we derive low-energy effective Hamiltonians from first principles. We show that the complex band structure around the Fermi level is represented only by the Fe 3 (mixed with 3) and 3 orbitals. The characteristic band degeneracy allows us to construct a four-band model with the band unfolding approach. We also estimate the interaction parameters and show that the system is more correlated than the 1111 family of iron-based superconductors. Provided the superconductivity is mediated by spin fluctuations, the -like band plays an essential role, and the gap function changes its sign between the Fermi surface around the point and that around the Brillouin-zone boundary.

6 pages, 7 figures

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