Self-energy behavior away from the Fermi surface in doped Mott insulators

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Mott insulators exhibit strong electron-electron correlations.
• Understanding electron behavior away from the Fermi surface is crucial for predicting material properties.
• The Hubbard model is a fundamental model for studying correlated electron systems.

Purpose of the Study:

• To investigate the behavior of electron self-energies away from the Fermi surface in doped Mott insulators.
• To analyze the influence of doping (hole vs. electron) on self-energy magnitudes.
• To determine the role of chemical potential shifts versus electronic correlations in observed self-energy enhancements.

Main Methods:

• Dynamical Cluster Approximation (DCA) applied to the Hubbard model.
• Analysis of electron self-energies at specific points in the Brillouin zone ([Formula: see text] and [Formula: see text]).
• Comparison of self-energy behavior in embedded clusters and isolated clusters with shifted chemical potentials.

Main Results:

• For hole doping in Mott insulators with large onsite repulsion (U), the self-energy at the top of the band is enhanced more than at the bottom.
• This self-energy enhancement trend reverses for electron doping.
• Isolated clusters with a downward chemical potential shift mimic the self-energy behavior of weakly hole-doped embedded clusters, even without electronic structure changes.

Conclusions:

• A downward shift in chemical potential, causing weak hole doping, can significantly enhance the self-energy for imaginary frequencies.
• This enhancement is not necessarily due to electronic correlation effects, especially for states away from the Fermi surface.
• Interpreting the strength of electronic correlations solely based on self-energies for imaginary frequencies can be misleading for states away from the Fermi surface.