title: Anomalous coulomb drag in electron-hole bilayers.
abstract: We report Coulomb drag measurements on GaAs-AlGaAs electron-hole bilayers. The two layers are separated by a 10 or 25 nm barrier. Below T approximately 1 K we find two features that a Fermi-liquid picture cannot explain. First, the drag on the hole layer shows an upturn, which may be followed by a downturn. Second, the effect is either absent or much weaker in the electron layer, even though the measurements are within the linear response regime. Correlated phases have been anticipated in these, but surprisingly, the experimental results appear to contradict Onsager's reciprocity theorem.
authors.affiliation: Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
authors.forename: A F
authors.initials: AF
authors.lastname: Croxall
authors.forename: K
authors.initials: K
authors.lastname: Das Gupta
authors.forename: C A
authors.initials: CA
authors.lastname: Nicoll
authors.forename: M
authors.initials: M
authors.lastname: Thangaraj
authors.forename: H E
authors.initials: HE
authors.lastname: Beere
authors.forename: I
authors.initials: I
authors.lastname: Farrer
authors.forename: D A
authors.initials: DA
authors.lastname: Ritchie
authors.forename: M
authors.initials: M
authors.lastname: Pepper