Work

Imaging tunable quantum Hall broken-symmetry orders in charge-neutral graphene

Year: 2022

Type: article

Abstract: Charge-neutral graphene under perpendicular magnetic field was predicted to harbor a rich variety of many-body ground states with distinct topological and symmetry breaking orders. We directly image the atomic-scale electronic wavefunction of three distinct broken-symmetry phases in graphene using scanning tunneling spectroscopy. We explore the phase diagram by controllably tuning the magnetic field and the screening of the Coulomb interaction by close proximity to a low or high dielectric constant substrate. In the unscreened case, we unveil a Kekulé bond order. Under dielectric screening, a sublattice-unpolarized ground state emerges at low magnetic fields, and transits to a charge-density-wave order with partial sublattice polarization at higher magnetic fields. In both cases we further observed the coexistence of additional, secondary lattice-scale orders. This screening-induced tunability of broken-symmetry orders may prove valuable to uncover correlated phases of matter in other quantum materials.

Source: HAL

DOI: 10.1038/s41586-022-04513-7