Tuning of quantum interference in top-gated graphene on SiC

Abstract

We report on quantum-interference measurements in top-gated Hall bars of monolayer graphene epitaxially grown on the Si face of SiC, in which the transition from negative to positive magnetoresistance was achieved varying temperature and charge density. We perform a systematic study of the quantum corrections to the magnetoresistance due to quantum interference of quasiparticles and electron-electron interaction. We analyze the contribution of the different scattering mechanisms affecting the magnetotransport in the −2.0 × 10 10 cm −2 to 3.75 × 10 11 cm −2 density region and find a significant influence of the charge density on the intravalley scattering time. Furthermore, we observe a modulation of the electron-electron interaction with charge density not accounted for by present theory. Our results clarify the role of quantum transport in SiC-based devices, which will be relevant in the development of a graphene-based technology for coherent electronics.

Enhanced intervalley scattering in artificially stacked double-layer graphene

“…The consistent characteristics in the Raman spectroscopy indicate that the layer-by-layer transfer of the CVD-grown graphene made a uniform quality of graphene with relatively low defects for the large area of the device in this experiment. Figure 1 uniformity and wrinkles were reported to affect the characteristic lengths of transport properties in the epitaxial graphene grown on SiC substrate [25,31,32].…”

Measurement of topological Berry phase in highly disordered graphene

“…STM imaging 21,22 has mapped the local density of states in the vicinity of both lone hydrogen adsorbates and hydrogen adsorbate pairs. Previous magnetotransport measurements show that the ν = 2 QHE state can be observed in hydrogenated graphene 16 , as well as in disordered graphene grown by sublimation of SiC 17,18 . Thus far, the topological Berry phase in highly disordered graphene has remained unmeasured.…”

Magnetoresistance of disordered graphene: From low to high temperatures

“…At intermediate magnetic fields, between the realms of weak localization and quantum Hall effect, recent measurements highlighted the role of the electron-electron interaction (EEI) on the magnetoconductivity. [6][7][8][9] A complete theory of EEI in graphene is still missing, but it is possible to use the knowledge accumulated in more conventional twodimensional systems like thin metal films or semiconductor heterostructures, for which EEI has been theoretically and experimentally studied over more than three decades [10][11][12][13][14][15]. The quantum correction due to the EEI differs at low and high temperatures.…”

“…In particular, in the ballistic regime, EEI depends on the impurity type [23] and can give indications on the microscopic nature of disorder in graphene. Up to now, most of the EEI measurements in graphene have focused on the diffusive regime [6][7][8][9]. The systematic study of EEI correction in this material, from the diffusive to the ballistic regime, associated with quantitative and qualitative comparisons with models of disorder, is still lacking.…”