  We study the coupling between the structural dynamics and rheological
response of charged colloidal monolayers at water/oil interfaces, driven into
steady shear by a microdisk rotating at a controlled angular velocity. The flow
causes particles to layer into rotating concentric rings linked to the local,
position-dependent shear rate, which triggers two distinct dynamical regimes:
particles move continuously "Flowing") close to the microdisk, or exhibit
intermittent "Hopping" between local energy minima farther away. The shear-rate
dependent surface viscosity of a monolayer can be extracted from an interfacial
stress balance, giving "macroscopic" flow curves whose behavior corresponds to
the distinct microscopic regimes of particle motion. Hopping Regions correspond
to a surface yield stress $\eta \sim \tau_S^Y \dot{\gamma}^{-1}$, whereas
Flowing Regions exhibit surface viscosities with power-law shear-thinning
characteristics.
