Nanowerk July 18, 2019
Solid ferromagnetic materials are rigid in shape and cannot be reconfigured. Ferrofluids, although reconfigurable, are paramagnetic at room temperature and lose their magnetization when the applied magnetic field is removed. An international team of researchers (USA – Lawrence Berkeley Laboratory, UC Santa Cruz, UC Berkeley, UMass Amherst, China, Japan) shows a reversible paramagnetic-to-ferromagnetic transformation of ferrofluid droplets by the jamming of a monolayer of magnetic nanoparticles assembled at the water-oil interface. The ferromagnetic liquid droplets exhibit a finite coercivity and remnant magnetization, they can be easily reconfigured into different shapes while preserving the magnetic properties of solid ferromagnets with classic north-south dipole interactions and their translational and rotational motions can be actuated remotely and precisely by an external magnetic field. The research opens promising research and application areas such as liquid actuators, liquid robotics and active-matter delivery…read more. TECHNICAL ARTICLE
Three liquid magnets float in the oil phase, spinning and dancing with each other in the rotating external magnetic field. Credit: Berkeley National Lab/Xubo Liu