Hydrodynamic and quasiballistic transport over large length scales in GaAs/AlGaAs.

We study hydrodynamic and ballistic transport regimes through nonlocal resistance measurements and high-resolution kinetic simulations in a mesoscopic structure on a high-mobility two-dimensional electron system in a GaAs/AlGaAs heterostructure. We evince the existence of collective transport phenomena in both regimes and demonstrate that a large-scale geometry on a high-mobility system manifests a sensitivity to even weak electron-electron interactions. The combined experiments and simulations allow extraction of the momentum-conserving electron-electron scattering length, shown to be longer than predicted by microscopic theories.