Probing electron correlations in solids with Auger-photoelectron coincidence spectroscopy

Area of Science:

• Solid-state physics
• Quantum chemistry
• Surface science

Background:

• Electron-electron correlation significantly impacts solid properties.
• Auger photoelectron coincidence spectroscopy (APECS) probes these correlations.
• Core-valence-valence (CVV) Auger transitions create final states with two holes, influenced by Coulomb and exchange interactions.

Purpose of the Study:

• To review the advantages and applications of APECS.
• To present a model for understanding APECS data and experimental design.
• To demonstrate APECS's capability in independently measuring correlation energies.

Main Methods:

• Simultaneous detection of photoelectrons and Auger electrons.
• Application of a phenomenological model for electron pair emission.
• Analysis of one-dimensional, two-dimensional, and angle-resolved APECS measurements.

Main Results:

• APECS offers superior spectral feature separation and background reduction compared to other methods.
• A presented model aids in interpreting APECS data based on kinetic energies and emission angles.
• Angle-resolved APECS successfully measured Coulomb and exchange correlation energies in ferromagnetic metals and antiferromagnetic oxides.

Conclusions:

• APECS is a powerful technique for detailed investigation of electron correlation in solids.
• The developed model facilitates APECS data analysis and experimental planning.
• Angle-resolved APECS provides independent measurement of fundamental correlation energies, crucial for understanding material properties.