Magnetic properties and pairing tendencies of the iron-based superconducting ladder BaFe2S3:Combined ab-initio and density matrix renormalization group study

The recent discovery of superconductivity in the two-leg ladder compound BaFe2S3[1] opens a broad avenue of research, because it represents the first report of pairing tendencies in a quasi-one-dimensional iron-based high-critical-temperature superconductor. As in the case of the cuprates, ladders and chains can be far more accurately studied using many-body techniques and model Hamiltonians than their layered counterparts. We study a two-orbital Hubbard model derived from first principles that describes individual ladders of BaFe2S3using density matrix renormalization group [2]. Two main results are found: (i)at half-filling, ferromagnetic (antiferromagnetic) order emerges as the dominant magnetic pattern along the rungs (legs) of the ladder, in excellent agreement with neutron experiments; and (ii)with hole doping, pairs form in the strong coupling regime, as found by studying the binding energy. In addition, we also find binding tendencies in 1D chain of two-orbitals where the pair-pair correlations show inter-orbital singlet pairs on the neighboring sites. [1] H. Takahashi et al., Nat. Mater. 14, 1008(2015) [2] N. D. Patel et al., Phys. Rev. B 94, 075119 (2016)