Commensurability Oscillations in One-Dimensional Graphene Superlattices

TL;DR

This paper reports the experimental observation of commensurability oscillations in one-dimensional graphene superlattices, demonstrating long mean free paths and temperature robustness, with implications for understanding scattering mechanisms in graphene heterostructures.

Contribution

It provides the first experimental evidence of COs in 1D graphene superlattices with tunable potentials and analyzes the dominant scattering mechanisms.

Findings

Observation of up to six CO minima in magneto-resistance.

COs persist above 150 K, indicating high-quality samples.

Small angle scattering dominates in hBN/graphene/hBN heterostructures.

Abstract

We report the experimental observation of commensurability oscillations (COs) in 1D graphene superlattices. The widely tunable periodic potential modulation in hBN encapsulated graphene is generated via the interplay of nanopatterned few layer graphene acting as a local bottom gate and a global Si back gate. The longitudinal magneto-resistance shows pronounced COs, when the sample is tuned into the unipolar transport regime. We observe up to six CO minima, providing evidence for a long mean free path despite the potential modulation. Comparison to existing theories shows that small angle scattering is dominant in hBN/graphene/hBN heterostructures. We observe robust COs persisting to temperature exceeding $T=150$ K. At high temperatures, we find deviations from the predicted $T$-dependence, which we ascribe to electron-electron scattering.