LAUSR

An ultra-thin film of a carrier liquid containing nanosize ferromagnetic particles sitting on a solid substrate and surrounded by an ambient gas phase can be acted upon, apart from viscous and capillary forces, by attractive van der Waals forces which may promote instability leading to film rupture and substrate dewetting. In this article we show that the collective rotation of the particles on the liquid–gas interface, due to a magnetic torque, competes against the instability induced by the van der Waals forces that tend to deepen depressions of the liquid. The competition between the two effects (forcing and instability) leads to the generation of a permanent nonlinear interfacial viscous–capillary wave. Thus, film rupture and substrate dewetting are both averted. This is a general effect that may also be employed to suppress other types of instabilities such as the Rayleigh–Taylor and thermocapillary instabilities. This effect has yet to be observed in experiment.