Strong localization in suspended monolayer graphene by intervalley scattering

Official URL: https://dx.doi.org/10.1103/PhysRevB.103.085437

A gate-induced insulating behavior at zero magnetic field is observed in a high-mobility suspended monolayer graphene near the charge neutrality point. The graphene device initially cleaned by a current annealing technique underwent a thermopressure cycle to allow short-range impurities to be adsorbed directly by the ultraclean graphene surface. The adsorption process generated a strong temperature- and electric-field-dependent behavior on the conductance of the graphene device. The conductance around the neutrality point is observed to be reduced from around e2/h at 30 K to ∼0.01e2/h at 20 mK. A direct transition from an insulator to a quantum Hall conductor within ≈0.4T accompanied by broken-symmetry-induced ν=0,±1 plateaus confirms the presence of intervalley scatterers.