Hund-Enhanced Electronic Compressibility in FeSe and its Correlation with T_{c}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Iron selenide (FeSe) exhibits complex electronic properties, including superconductivity.
• Understanding electron correlations is crucial for explaining FeSe's behavior.
• Hund's metals phenomenology offers a framework for correlated electron systems.

Purpose of the Study:

• To compute the electronic compressibility of bulk and monolayer FeSe.
• To investigate the role of dynamical electronic correlations.
• To correlate compressibility with superconductivity enhancement.

Main Methods:

• Slave-spin mean-field theory combined with density-functional theory (SSMF+DFT).
• Analysis of electronic compressibility across interaction-doping phase diagrams.
• Comparison between bulk FeSe and monolayer FeSe on SrTiO3 substrate.

Main Results:

• A zone of enhanced electronic compressibility was identified, consistent with Hund's metal phenomenology.
• Bulk FeSe moves into this enhanced zone under hydrostatic pressure.
• Monolayer FeSe shows stronger compressibility enhancement on the electron-doped side.

Conclusions:

• Enhanced electronic compressibility correlates with increased superconductivity in FeSe.
• Hund's metal physics and many-body correlations likely play a key role in superconductive pairing.
• Pressure and doping are critical factors in tuning FeSe's electronic properties for superconductivity.