Snake trajectories in ultraclean graphene p-n junctions

Area of Science:

• Condensed matter physics
• Quantum transport phenomena
• Materials science

Background:

• Snake states are charge carrier trajectories that curve along interfaces.
• Two types exist: magnetic field inversion and charge carrier type inversion.
• Previous demonstrations were limited to specific heterostructures (e.g., GaAs-AlGaAs).

Purpose of the Study:

• To experimentally observe snake states in ballistic graphene.
• To investigate snake states formed by charge carrier type inversion at a graphene p-n junction.
• To demonstrate the role of Klein tunneling and collimation in snake state visibility.

Main Methods:

• Fabrication of a ballistic suspended graphene p-n junction.
• Measurement of magneto-conductance oscillations at low magnetic fields (20 mT).
• Utilizing Klein collimation to enhance snake state visibility (30%).
• Validation through quantum transport simulations.

Main Results:

• Observation of magneto-conductance oscillations attributed to snake states.
• Demonstration of snake states in graphene at low magnetic fields.
• Evidence of high device tunability and operation across different magnetic field regimes.

Conclusions:

• Snake states formed by charge carrier type inversion are experimentally realized in graphene.
• Klein collimation significantly enhances the visibility of these snake states.
• The findings open new avenues for exploring quantum phenomena in graphene-based devices.