Hydrodynamic and ballistic transport over large length scales in GaAs/AlGaAs

Hydrodynamic and ballistic transport regimes are investigated through nonlocal resistance measurements and high-resolution kinetic simulations in a mesoscopic structure on a high-mobility 2D electron system in a GaAs/AlGaAs heterostructure over a temperature range 4 K < T < 40 K, at zero magnetic field. The nonlocal measurements are performed in a large-scale (∼30 × 24 μm) ultraclean (electron mean free path ∼ 65 μm at 4.2 K) device, which by its scale offers exceptional sensitivity to electron-electron scattering, featuring 10 point contacts to probe voltages at various distances from the current injection contacts. The one-to-one simulations, involving the actual experimental geometry in the precise contact configuration, and taking into account both momentum relaxing and momentum conserving scattering, determine that the device transitions from a predominantly ballistic regime at T= 4.2 K to a hydrodynamic regime at T ≈ 10...15 K. The combined experiments and simulations reveal the existence of collective transport phenomena in both regimes, highlighting that negative nonlocal resistance and current vortices are not exclusive to the hydrodynamic regime.