Viscous Electron Flow and Nonlinear Magnetotransport in 2D Channels

We examine nonlinear transport in a viscous two-dimensional electron fluid within narrow GaAs channels. The differential magnetoresistance shows nonmonotonic behavior, a signature of electron pairing in the hydrodynamic regime. Theoretical models that account for both the influence of these interactions on shear stress relaxation and viscosity changes from electron heating show good agreement with the data. The nonlinear regime thus reveals how such correlated states govern the hydrodynamic behavior of the electron fluid. Our findings establish the nonlinear transport regime as a powerful probe for dissecting the complex interplay of correlated electron states and momentum relaxation in the hydrodynamic flow of an electron fluid.