Directional control of charge and valley currents in a graphene-based device

Area of Science:

• Condensed matter physics
• Materials science
• Nanotechnology

Background:

• Graphene's unique electronic properties, including its distinct electronic bands (valleys), offer potential for advanced electronic devices.
• Valleytronics, which utilizes the valley degree of freedom of electrons, is an emerging field with promise for low-power electronics.

Purpose of the Study:

• To investigate and demonstrate a directional switching effect in a graphene-based device.
• To explore the control of unidirectional charge and valley currents using external stimuli.
• To establish the foundation for active graphene-based valleytronics.

Main Methods:

• Fabrication of a three-terminal graphene device.
• Application of a magnetic field to the device.
• Control of Fermi energy levels.
• Measurement of charge and valley currents.
• Quantification of valley depolarization under varying disorder concentrations.

Main Results:

• Demonstration of a directional switching effect in the metallic graphene device.
• Unidirectional charge and valley currents were successfully controlled by Fermi energy and magnetic field direction.
• Unidirectional transport was observed between two terminals at the same bias voltage.
• Valley depolarization was quantified as a function of disorder concentration.

Conclusions:

• The proposed directional switching effect is achievable in graphene devices.
• The findings highlight the potential for controlling charge and valley currents for spintronics and valleytronics.
• This research opens avenues for the development of active graphene-based valleytronics devices.