Abstract

Magnetic materials hold tremendous potential for precision control of matter due to their tunable interactions in dynamic magnetic fields. Flexible superparamagnetic filaments and membranes under the influence of precessing magnetic fields, for example, can exert controllable forces to generate microscopic actuation. We characterize the resulting changes of shapes in terms of their material parameters, as well as of the strength of the magnetic field. In particular, we show how by controlling the magnetic field, open membranes may form either rippled or helicoidal surfaces, whereas closed membranes can buckle into convex and concave shapes with specific symmetries. Shape control via magnetic fields is also discussed in three-dimensional gels reinforced with ferromagnetic matter. These systems might be suitable for constructing devices with controllable conformational changes such as artificial muscles.