  The hydrodynamic behavior of electron fluids in a certain range of
temperatures and densities is well established in graphene and in 2D
semiconductor heterostructures. The hydrodynamic regime is intrinsically based
on electron-electron interactions, and therefore it provides a unique
opportunity to study electron correlations. Unfortunately, in all existing
measurements, the relative contribution of hydrodynamic effects to transport is
rather small. Viscous hydrodynamic effects are masked by impurities,
interaction with phonons, uncontrolled boundaries and ballistic effects. This
essentially limits the accuracy of measurements of electron viscosity.
Fundamentally, what causes viscous friction in the electron fluid is the
property of the flow called vorticity. In this paper, we propose to use
micromagnets to increase the vorticity by orders of magnitude. Experimental
realization of this proposal will bring electron hydrodynamics to a
qualitatively new precision level, as well as opening a new way to characterize
and externally control the electron fluid.
