Negative local resistance caused by viscous electron backflow in graphene

• DOI: 10.1126/science.aad0201
• Publication Date: 2016-02-12T05:23:23Z
• Authors: D. A. Bandurin; I. Torre; R. Krishna Kumar; M. Ben Shalom; A. Tomadin; A. Principi; G. H. Auton; E. Khestanova; K. S. Novoselov; I. V. Grigorieva; L. A. Ponomarenko; A. K. Geim; M. Polini
• Keywords: Backflow; Negative resistance

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 viscous and exhibit hydrodynamic phenomena similar 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, attributed formation submicrometer-size whirlpools flow. The viscosity graphene's be ~0.1 square meters per second, order magnitude higher than honey, agreement with many-body theory. Our work demonstrates possibility studying hydrodynamics using high-quality graphene.