Emerging many-body effects in semiconductor artificial graphene with low disorder

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Electron-electron interactions and honeycomb topology can lead to exotic quantum phenomena.
• Semiconductor-based artificial graphene (AG) offers a platform to study these effects due to its high-mobility electron gases and AG topology.
• Achieving low-disorder conditions in AG has been a significant challenge, hindering the study of electron-electron interactions with AG symmetry.

Purpose of the Study:

• To create low-disorder artificial graphene (AG) that preserves the quality of the electron layer.
• To investigate the interplay between electron-electron interactions and the honeycomb topology in AG.
• To explore potential applications of such systems in advanced devices.

Main Methods:

• Fabrication of small period triangular antidot lattices on high-quality quantum wells to create low-disorder AG.
• Utilizing resonant inelastic light scattering spectroscopy to probe electronic properties.
• Analysis of collective spin-exciton modes and Coulomb exchange interaction energies.

Main Results:

• Successfully created low-disorder AG, maintaining the high quality of the electron layer.
• Observed collective spin-exciton modes at the M-point's saddle-point singularity in the density of states.
• Demonstrated that Coulomb exchange interaction energies are comparable to the Dirac band gap, confirming the interplay between quasiparticle interactions and the AG potential.

Conclusions:

• Low-disorder AG systems enable the study of electron-electron interactions and AG topology.
• The observed phenomena, particularly saddle-point excitons in the terahertz range, suggest suitability for contemporary optoelectronic applications.
• This work paves the way for exploring novel quantum phenomena and device applications in artificial graphene.