Valley filtering in graphene due to substrate-induced mass potential

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Graphene's unique electronic properties, such as sublattice symmetry breaking by substrates, lead to unidirectional chiral states.
• These chiral states offer potential for novel electronic devices like valley filters.

Purpose of the Study:

• To propose and investigate a graphene-based valley filter utilizing a substrate-induced mass kink.
• To explore the transport properties and valley filtering efficiency of this novel graphene device.

Main Methods:

• Solving the time-dependent Schrödinger equation for the tight-binding Hamiltonian.
• Simulating the time evolution of a Gaussian wave packet through the proposed structure.
• Analyzing the transport properties of the graphene quantum point contact.

Main Results:

• Efficient valley filtering is achieved for low-energy electrons within the lowest sub-band.
• Optimal filtering requires specific channel dimensions (long and narrow).
• Valley polarization demonstrates robustness against impurities and defects within the channel.

Conclusions:

• The proposed substrate-induced mass kink is an effective mechanism for creating a graphene valley filter.
• The device shows promise for applications requiring high valley polarization, even in the presence of imperfections.
• Further research can optimize device design for enhanced performance in low-energy electronics.