Spontaneous liquid crystal and ferromagnetic ordering of colloidal magnetic nanoplates

• Published in: Nature communications Vol. 7; no. 1; p. 10394
• Main Authors: Shuai, M., Klittnick, A., Shen, Y., Smith, G. P., Tuchband, M. R., Zhu, C., Petschek, R. G., Mertelj, A., Lisjak, D., Čopič, M., Maclennan, J. E., Glaser, M. A., Clark, N. A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 28.01.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/2793; 639/301/357/354; 639/301/923/919; 639/766/189; Humanities and Social Sciences; multidisciplinary; NANOSCIENCE AND NANOTECHNOLOGY; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10394

Ferrofluids are familiar as colloidal suspensions of ferromagnetic nanoparticles in aqueous or organic solvents. The dispersed particles are randomly oriented but their moments become aligned if a magnetic field is applied, producing a variety of exotic and useful magnetomechanical effects. A longstanding interest and challenge has been to make such suspensions macroscopically ferromagnetic, that is having uniform magnetic alignment in the absence of a field. Here we report a fluid suspension of magnetic nanoplates that spontaneously aligns into an equilibrium nematic liquid crystal phase that is also macroscopically ferromagnetic. Its zero-field magnetization produces distinctive magnetic self-interaction effects, including liquid crystal textures of fluid block domains arranged in closed flux loops, and makes this phase highly sensitive, with it dramatically changing shape even in the Earth’s magnetic field. Ferromagnetism has been known as a material property of solids since the time of the ancient Greeks. Here, Shuai et al . report that magnetic nanoplates suspended in a simple solvent can spontaneously align to form a ferromagnetic liquid, capable of both producing and sensing magnetic fields.