Electronic cooling via interlayer Coulomb coupling in multilayer epitaxial graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• In layered two-dimensional (2D) materials, electronic states are confined within layers, limiting interlayer transport.
• Weak van der Waals forces result in poor thermal coupling between layers, hindering heat dissipation.
• Electron-phonon interactions are typically confined to within individual layers.

Purpose of the Study:

• To investigate the role of interlayer Coulomb interactions in thermal transport in multilayer epitaxial graphene.
• To demonstrate an alternative mechanism for heat transfer beyond phonon-mediated coupling.
• To explain the observed hot-carrier dynamics in ultrafast spectroscopy experiments.

Main Methods:

• Ultrafast time-resolved terahertz spectroscopy to probe hot-carrier dynamics.
• Development of a theoretical model for interlayer Coulomb coupling.
• Experimental variation of temperature and number of layers to observe trends.

Main Results:

• Coulomb interactions between electrons in different layers facilitate significant interlayer thermal transport.
• This Coulombic mechanism is effective even with strong electron confinement within individual 2D layers.
• The developed theory accurately predicts experimental observations without free parameters.

Conclusions:

• Interlayer Coulomb interactions represent a key pathway for thermal transport in multilayer 2D materials.
• This mechanism challenges the conventional understanding of heat transfer limitations in such systems.
• The findings have implications for thermal management in nanoscale electronic devices.