Negative local resistance caused by viscous electron backflow in graphene

By D. Bandurin, I. Torre, R. K. Kumar, M. Shalom, A. Tomadin, A. Principi, G. Auton, E. Khestanova, K. Novoselov, I. V. Grigorieva and 3 more. Science, 2015

660 citations recorded by the source corpus.

Electrons that flow like a fluid Electrons inside a conductor are often described as flowing in response to an electric field. This flow rarely resembles anything like the familiar flow of water through a pipe, but three groups describe counterexamples (see the Perspective by Zaanen). Moll et al. found that the viscosity of the electron fluid in thin wires of PdCoO2 had a major effect on the flow, much like what happens in regular fluids. Bandurin et al. found evidence in graphene of electron whirlpools similar to those formed by viscous fluid flowing through a small opening. Finally, Crossno et al. observed a huge increase of thermal transport in graphene, a signature of so-called Dirac fluids. Science, this issue p. 1061, 1055, 1058; see also p. 1026 Proximity transport measurements find evidence of whirlpools of graphene’s viscous electronic fluid. [Also see Perspective by Zaanen] Graphene hosts a unique electron system in which electron-phonon scattering is extremely weak but electron-electron collisions are sufficiently frequent to provide local equilibrium above the temperature of liquid nitrogen. Under these conditions, electrons can behave as a viscous liquid and exhibit hydrodynamic phenomena similar to classical liquids. Here we report strong evidence for this transport regime. We found that doped graphene exhibits an anomalous (negative) voltage drop near current-injection contacts, which is attributed to the formation of submicrometer-size whirlpools in the electron flow. The viscosity of graphene’s electron liquid is found to be ~0.1 square meters per second, an order of magnitude higher than that of honey, in agreement with many-body theory. Our work demonstrates the possibility of studying electron hydrodynamics using high-quality graphene.

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/4b66f21a5d0bb8618f8cbb0eae90110d1cc05c0e

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Citations in the corpus

Holographic Quantum Matter (2016, methodology): “Hence, we expect the viscous ‘backflow’ signature of [66] to vanish near charge neutrality.”
Fracton hydrodynamics (2020, background): “[6] D.”
Lecture notes on Generalised Hydrodynamics (2019, background): “[13, 14], as well as the large amount of progress done in the context of electron flows in graphene-based systems [15, 16, 17, 18], which has had experimental evidence [19, 20, 21].”
Polaritons in van der Waals materials (2016, background): “Ultrafast heating of electrons and plasmons may realize a regime in which the dynamics of an approximately equal number of electrons and holes in graphene resembles the behavior of viscous liquids described by relativistic hydrodynamics (34, 35).”
Relativistic Fluid Dynamics in and out of Equilibrium (2017, background): “Besides the application to relativistic nuclear collisions mentioned in chapter 5, other systems, such as the strongly correlated electron fluid in graphene [418] and non-relativistic applications such as cold quantum gases near unitarity [419], and high-temperature superconductors [420] are likely ”