Selective Mott physics as a key to iron superconductors.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Chemistry

Background:

• BaFe(2)As(2) is a key material in studying superconductivity and correlated electron phenomena.
• Understanding the role of electron correlations is crucial for designing new materials with desired electronic properties.

Purpose of the Study:

• To investigate the influence of Mott insulating states on electron- and hole-doped BaFe(2)As(2).
• To elucidate the mechanism behind the coexistence of weakly and strongly correlated electrons.
• To explore the relationship between doping, Hund's coupling, and electronic correlations in this material system.

Main Methods:

• Experimental studies on electron- and hole-doped BaFe(2)As(2) samples.
• Analysis of the phase diagram to observe variations in electron correlation strength.
• Theoretical consideration of Hund's coupling effects on charge excitations across different orbitals.

Main Results:

• Both electron- and hole-doped BaFe(2)As(2) are significantly influenced by a Mott insulator state.
• Weakly and strongly correlated electrons coexist across the phase diagram, with increasing differentiation upon hole doping.
• Hund's coupling decouples charge excitations, leading to each orbital behaving as a single-band doped Mott insulator.

Conclusions:

• The electronic correlation strength in BaFe(2)As(2) is modulated by orbital-dependent doping levels relative to half-filling.
• A strong asymmetry exists between hole and electron doping effects.
• This work establishes a significant connection between the electronic properties of iron-based superconductors and cuprates.