Surface Dynamics of Chiral Colloidal Gyrofluids*

Colloidal magnets, when spun by a rotating external field, coalesce into a fluid-like state. This fluid exhibits rich interfacial dynamics, which we explore in this talk. In particular, we observe experimentally and explain theoretically the propagation and dissipation of chiral surface waves. Unlike capillary waves in water, their propagation relies neither on inertia nor on surface tension. In contrast viscosity and spinning motion conspire against surface tension to sustain their unidirectional propagation.