Ultra-flat and long-lived plasmons in a strongly correlated oxide

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Plasmons in strongly correlated systems display unique behaviors due to electronic correlations.
• Flat plasmons, characterized by dispersionless frequency-wave vector relations, are of significant interest.
• Previous observations of flat plasmons were limited to low-dimensional materials and smaller wave vector magnitudes (q < ~0.7 Å⁻¹).

Purpose of the Study:

• To investigate the existence and properties of flat plasmons in three-dimensional strongly correlated systems.
• To explore the potential for long-lived flat plasmons in materials beyond low-dimensional systems.
• To understand the underlying mechanisms responsible for flat plasmon behavior in Mott insulators.

Main Methods:

• Theoretical investigation of electronic band structure in alpha-Ti2O3.
• Analysis of plasmon dispersion and damping mechanisms.
• Utilizing symmetry constraints to understand Landau damping effects.

Main Results:

• Long-lived flat plasmons were observed propagating up to ~1.2 Å⁻¹ in alpha-Ti2O3, a 3D Mott-insulator.
• These flat plasmons exhibit ultra-small energy fluctuations (<40 meV).
• Strong electronic correlation effects renormalize the electronic bands, leading to a small bandwidth responsible for the flat plasmons.
• Flat plasmons are robust against Landau damping due to symmetry constraints on electron wavefunctions up to ~1.2 Å⁻¹.

Conclusions:

• Alpha-Ti2O3 hosts long-lived flat plasmons in a 3D strongly correlated system.
• The findings provide a pathway for discovering flat plasmons in other correlated materials.
• This research opens avenues for developing novel plasmonic devices utilizing flat and long-lived plasmons.