Negative local resistance caused by viscous electron backflow in graphene

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…

• LR
  Lloyd's Register Foundation
• RS
  Royal Society
• EA
  Engineering and Physical Sciences Research Council

  Awards: EP/K005014/1, EP/M003167/1, EP/G02491X/1
• HE
  H2020 European Research Council