Reconfigurable ferromagnetic liquid droplets

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. Here, we show a reversible paramagnetic-to-ferromagnetic transformation of...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2019-07, Vol.365 (6450), p.264-267
Main Authors: Liu, Xubo, Kent, Noah, Ceballos, Alejandro, Streubel, Robert, Jiang, Yufeng, Chai, Yu, Kim, Paul Y, Forth, Joe, Hellman, Frances, Shi, Shaowei, Wang, Dong, Helms, Brett A, Ashby, Paul D, Fischer, Peter, Russell, Thomas P
Format: Article
Language:English
Subjects:
Coercivity
Crystals
Cylinders
Dipole interactions
Droplets
Ferrofluids
Ferromagnetic materials
Jamming
Magnetic dipoles
Magnetic fields
Magnetic properties
Magnetism
Magnetite
Magnetization
MATERIALS SCIENCE
Mud-water interfaces
Nanoparticles
Reconfiguration
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Summary: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. Here, we show a reversible paramagnetic-to-ferromagnetic transformation of ferrofluid droplets by the jamming of a monolayer of magnetic nanoparticles assembled at the water-oil interface. These ferromagnetic liquid droplets exhibit a finite coercivity and remanent magnetization. They can be easily reconfigured into different shapes while preserving the magnetic properties of solid ferromagnets with classic north-south dipole interactions. Their translational and rotational motions can be actuated remotely and precisely by an external magnetic field, inspiring studies on active matter, energy-dissipative assemblies, and programmable liquid constructs.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.aaw8719