Tuning equilibration of quantum Hall edge states in graphene – Role of crossed electric and magnetic fields

• We create tunable superlattice in graphene.
• Probe quantum Hall physics in unipolar and bipolar 1D superlattice.
• Lack of equilibration resulting in smaller Hall resistances than expected.
• Equilibration is tuned in the bipolar regime by large electric field.
• Electric field tunes the Landau level mixing and wavefunctions.
• This tunability is unique to quantum Hall physics in graphene.

We probe quantum Hall effect in a tunable 1-D lateral superlattice (SL) in graphene created using electrostatic gates. Lack of equilibration is observed along edge states formed by electrostatic gates inside the superlattice. We create strong local electric field at the interface of regions of different charge densities. Crossed electric and magnetic fields modify the wavefunction of the Landau Levels (LLs) – a phenomenon unique to graphene. In the region of copropagating electrons and holes at the interface, the electric field is high enough to modify the Landau levels resulting in increased scattering that tunes equilibration of edge states and this results in large longitudinal resistance.