Theoretical study on the iron-based ladder: metal-insulator and antiferromagnetic transitions

The recent discovery of superconductivity in BaFe₂X₃ (X=S/Se) under high pressure has stimulated researchers’ enthusiasm for the study of 123-type iron chalcogenides. These materials own quasi-one-dimensional two-leg ladders, which is structurally and thus physically different from previously studied iron-based superconductors with two-dimensional iron sheets. For the S-based case, our first-principles calculations show that the lattice constants as well as local magnetic moments are gradually suppressed with increasing pressure, followed by a first-order magnetic transition at a critical pressure^[1]. The self-doping effect, namely the electrons transfer from S to Fe, may play a key role in this transition^[1]. Although the superconducting dome has also been reported in the Se-based case, our calculations on BaFe₂Se₃ have unveiled several qualitative differences from BaFe₂S₃. Sequential transitions, including structural, electronic, and magnetic transitions, are found with increasing pressure^[2].
[1] Y. Zhang, L. F. Lin, J. J. Zhang, E. Dagotto, and S. Dong, Phys. Rev. B 95, 115154 (2017).
[2] Y. Zhang, L. F. Lin, J. J. Zhang, E. Dagotto, and S. Dong, Phys. Rev. B, (under review).