Hydrodynamic electron flow in a graphene-based device with engineered edge conditions*

Hydrodynamic electron flow is expected to emerge in the regime where electron-electron interactions dominate over all other interactions. In this regime, electrons should flow like a viscous fluid. Evidence of such behavior in graphene has been found experimentally in the form of superballistic flow through constrictions [1] and negative local resistance measurements [2]. Hydrodynamic electron transport may strongly depend on boundary conditions, which can range from no-slip (all tangential momentum is dissipated at the boundary) to no-stress (the boundary exerts no force on the fluid). To isolate the impact of boundary conditions on hydrodynamic electron flow, we have fabricated a graphene device in a pipe geometry with the first half of the pipe having smooth edges and the second half having jagged edges. Through a combination of simulations and transport measurements with this device, we tune between the two extreme boundary conditions and identify the impact of edge geometry on the flow profile of a viscous electron fluid.

[1] Kumar, R. K., et al. Nature Physics 13(12), 1182 (2017)
[2] Bandurin, D. A., et al. Science 351(6277) 1055 (2016)