title: Anomalous low-temperature Coulomb drag in graphene-GaAs heterostructures.
abstract: Vertical heterostructures combining different layered materials offer novel opportunities for applications and fundamental studies. Here we report a new class of heterostructures comprising a single-layer (or bilayer) graphene in close proximity to a quantum well created in GaAs and supporting a high-mobility two-dimensional electron gas. In our devices, graphene is naturally hole-doped, thereby allowing for the investigation of electron-hole interactions. We focus on the Coulomb drag transport measurements, which are sensitive to many-body effects, and find that the Coulomb drag resistivity significantly increases for temperatures <5-10 K. The low-temperature data follow a logarithmic law, therefore displaying a notable departure from the ordinary quadratic temperature dependence expected in a weakly correlated Fermi-liquid. This anomalous behaviour is consistent with the onset of strong interlayer correlations. Our heterostructures represent a new platform for the creation of coherent circuits and topologically protected quantum bits.
authors.affiliation: National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze-Consiglio Nazionale delle Ricerche and Scuola Normale Superiore, I-56126 Pisa, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Gamucci
authors.affiliation: National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze-Consiglio Nazionale delle Ricerche and Scuola Normale Superiore, I-56126 Pisa, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Spirito
authors.affiliation: National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze-Consiglio Nazionale delle Ricerche and Scuola Normale Superiore, I-56126 Pisa, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Carrega
authors.affiliation: National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze-Consiglio Nazionale delle Ricerche and Scuola Normale Superiore, I-56126 Pisa, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Karmakar
authors.affiliation: Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK.
authors.forename: A
authors.initials: A
authors.lastname: Lombardo
authors.affiliation: Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK.
authors.forename: M
authors.initials: M
authors.lastname: Bruna
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08540, USA.
authors.forename: L N
authors.initials: LN
authors.lastname: Pfeiffer
authors.affiliation: Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08540, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: West
authors.affiliation: Cambridge Graphene Centre, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK.
authors.forename: A C
authors.initials: AC
authors.lastname: Ferrari
authors.affiliation: 1] National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze-Consiglio Nazionale delle Ricerche and Scuola Normale Superiore, I-56126 Pisa, Italy [2] Istituto Italiano di Tecnologia, Graphene labs, Via Morego 30, I-16163 Genova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Polini
authors.affiliation: 1] National Enterprise for Nanoscience and Nanotechnology (NEST), Istituto Nanoscienze-Consiglio Nazionale delle Ricerche and Scuola Normale Superiore, I-56126 Pisa, Italy [2] Istituto Italiano di Tecnologia, Graphene labs, Via Morego 30, I-16163 Genova, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Pellegrini