Gurzhi effect in point contacts in GaAs

Hydrodynamic electron transport through point contacts of different widths in two-dimensional electron gas in GaAs/AlGaAs heterostructure is studied. Effect Gurzhi, i.e., minimum in the temperature dependence of the point contact resistance, corresponding to the conductance exceeding the ballistic limit, is experimentally observed. The minimum is shown to be observed in case when electron-electron scattering length is comparable with the point contact width. Under this condition, electrons act as viscous fluid, that leads to the resistance reduction. The experimental data including the width dependence are consistent with the theoretical prediction of the viscous contribution to the point contact conductance.