Disorder-assisted electron-phonon scattering and cooling pathways in graphene

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Electron-lattice cooling is crucial for understanding thermal transport in materials.
• Momentum-conserving electron-phonon scattering in graphene is limited by its small Fermi surface, restricting energy transfer per collision.
• Existing cooling mechanisms may not fully explain thermal behavior in graphene at higher temperatures.

Purpose of the Study:

• To investigate the dominant electron-lattice cooling mechanism in graphene.
• To explore the role of disorder-assisted scattering (supercollisions) in electron cooling.
• To identify experimental signatures and potential applications of this cooling mechanism.

Main Methods:

• Theoretical prediction of electron-lattice cooling mechanisms in graphene.
• Analysis of electron-phonon scattering considering the unique electronic structure of graphene.
• Modeling of temperature dependence and cooling dynamics.

Main Results:

• Disorder-assisted scattering (supercollisions) is predicted to be the dominant electron-lattice cooling mechanism in graphene across a wide temperature range, including room temperature.
• The limited energy transfer per collision in momentum-conserving electron-phonon scattering, due to graphene's small Fermi surface, drives this dominance.
• Characteristic T^3 temperature dependence and power-law cooling dynamics are identified as key experimental signatures.

Conclusions:

• Graphene exhibits a unique electron-lattice cooling mechanism dominated by supercollisions, distinct from conventional cooling processes.
• The cooling rate is highly tunable by controlling the level of disorder, opening avenues for novel applications.
• Understanding this mechanism is vital for developing advanced electronic devices that utilize hot-carrier transport.