Made to order | Nature Physics

Access through your institution Buy or subscribe Hydrodynamics and magnetism meet spectacularly in ferrofluids — liquids containing magnetic nanoparticles. The ferrohydrodynamic magic

happens when an amount of ferrofluid is put on a superhydrophobic surface and exposed to a magnetic field. The forces at play, notably the liquid's surface tension and the tendency of

the magnetic particles to align with the field, result in a hedgehog-like droplet crystal (pictured). Holger Kadau and colleagues have now observed this phenomenon, known as the Rosensweig

instability, for a quantum ferrofluid (_Nature_ http://doi.org/bcf4; 2016) — a Bose–Einstein condensate (BEC) with strong magnetic dipolar interactions. The authors cooled down a gas of

164Dy atoms and created a BEC of about 15,000 atoms at a temperature of 70 nK. The atoms were held in a pancake-shaped trap and subjected to an external magnetic field of approximately 0.7

mT, which aligned their magnetic moments perpendicularly to the 'pancake' containing the atomic ensemble. This is a preview of subscription content, access via your institution

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about institutional subscriptions * Read our FAQs * Contact customer support Authors * Bart Verberck View author publications You can also search for this author inPubMed Google Scholar

RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Verberck, B. Made to order. _Nature Phys_ 12, 205 (2016). https://doi.org/10.1038/nphys3688 Download

citation * Published: 01 March 2016 * Issue Date: March 2016 * DOI: https://doi.org/10.1038/nphys3688 SHARE THIS ARTICLE Anyone you share the following link with will be able to read this

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