Electronic structure indicating a Mott insulator–metal transition and possible superconductivity in <i>A</i> Fe ₂ Q ₃ (A=Ca, Ba, Sr; Q=S, Se) compounds: A DFT+U study

In this paper, we report an ab-initio investigation on the electronic structure of iron-based ladder compounds AFe[Formula: see text] ([Formula: see text], Ba, Sr; [Formula: see text], Se). By gradually varying the pressure, the studied systems become metallic and the stripe-type antiferromagnetic (AFM) order disappears and is replaced by the nonmagnetic (NM) state. Magnetic moments vanish at different pressures in the studied two-leg ladder materials. The insulator–metal transitions, accompanied by the quenching of local magnetic moments and the reduction of electron correlation effects under pressure, are crucial in elucidating the Mott nature of the system. On the other hand, the density of states at the Fermi level [Formula: see text], the van Hove singularity energy ([Formula: see text]), the band structures and the Fermi surfaces are also studied and are used as criteria in order to select possible superconducting materials. Experiments are strongly solicited to confirm the nature of the observed transitions and the potential metallic or superconductivity character in the studied hypothetical systems under pressure.