Time-modulated chiral matter

In passive matter, structure and shape are dictated by effective interactions that are a function of the separation and orientation of the material's building blocks. Driving materials out of equilibrium allows these interactions to depend on time. We drive a collection of colloidal magnets to rotate with an angular speed that slows the rotation of the constituents at specific moments in time. The resulting interplay between spatial and temporal order provides effective control of internal structure, global morphology, and free surface stability. We interpret our observations in terms of the competition between time-modulated internal stresses and surface forces.