title: Giant Frictional Drag in Double Bilayer Graphene Heterostructures.
abstract: We study the frictional drag between carriers in two bilayer graphene flakes separated by a 2-5 nm thick hexagonal boron nitride dielectric. At temperatures (T) lower than ∼10  K, we observe a large anomalous negative drag emerging predominantly near the drag layer charge neutrality. The anomalous drag resistivity increases dramatically with reducing T, and becomes comparable to the layer resistivity at the lowest T=1.5  K. At low T the drag resistivity exhibits a breakdown of layer reciprocity. A comparison of the drag resistivity and the drag layer Peltier coefficient suggests a thermoelectric origin of this anomalous drag.
authors: Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA.
authors: Kayoung
authors: K
authors: Lee
authors: Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA.
authors: Jiamin
authors: J
authors: Xue
authors: Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA.
authors: David C
authors: DC
authors: Dillen
authors: National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan.
authors: Kenji
authors: K
authors: Watanabe
authors: National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan.
authors: Takashi
authors: T
authors: Taniguchi
authors: Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA.
authors: Emanuel
authors: E
authors: Tutuc