Anomalous low-temperature Coulomb drag in graphene-GaAs heterostructures

• Published in: Nature communications Vol. 5; no. 1; p. 5824
• Main Authors: Gamucci, A., Spirito, D., Carrega, M., Karmakar, B., Lombardo, A., Bruna, M., Pfeiffer, L. N., West, K. W., Ferrari, A. C., Polini, M., Pellegrini, V.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19.12.2014; Nature Publishing Group
• Subjects: 639/301/119; 639/766/483; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms6824

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. Ultrathin layers that can confine electron motion to just two dimensions exhibit a wide range of unusual electronic properties. Gamucci et al . combine two very different examples of such systems—graphene and a gallium arsenide quantum well—and demonstrate interlayer coupling effects.