Electronic Structure and Mott Localization in Iron Deficient TlFe₁.₅Se₂ with Superstructures

Original · EN

Electronic structure and magnetic properties for iron deficient TlFe₂₋ₓSe₂ compounds are studied by first-principles calculations. We find that for the case of x=0.5 with a Fe-vacancy ordered orthorhombic superstructure, the ground state exhibits a stripe-like antiferromagnetic ordering and opens a sizable band gap if the short-ranged Coulomb interaction of Fe-3d electrons is moderately strong, manifesting a possible Mott insulating state. While increasing Fe-vacancies from the x=0 side, where the band structure is similar to that of a heavily electron-doped FeSe system, the Mott localization can be driven by kinetic energy reduction as evidenced by the band narrowing effect. Implications of this scenario in the recent experiments on TlFe₂₋ₓSe₂ are discussed.