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Combining the properties of gases, crystals and superfluids to a single unique state of matter

We generated a quantum fluid made of tiny magnets, that are atoms of the most magnetic element dysprosium. We call it a “quantum ferrofluid” since it is superfluid and has magnetic properties similar to classical ferrofluids. Ferrofluids consist of ferromagnetic nanoparticles dissolved in oil or water. When a strong magnetic field is applied perpendicular to the surface of the ferrofluid it undergoes a so-called Rosensweig instability. The surface is no longer smooth like normal fluids, but it generates a regular thorny surface resembling a hedgehog. From the point view of the tiny magnets in a ferrofluid, every south- and northpole attract each other. Therefore, it is energetically favourable to be on top of each other along the field direction, so the fluid grows peaks out of the smooth surface.

For our investigations, described in the journal “Nature”, we created a quantum ferrofluid with 15,000 atoms and induced a magnetic instability. We observed then the emergence of regular patterns consisting of microscopic droplets, similar to the Rosensweig instability of ferrofluids. Each droplet has a radius smaller than 1 µm and their existence was not expected with the current state of research on these systems. Their observation could thus lead to a new field of research, as the researchers expect quantum fluctuations, related to Heisenberg’s uncertainty principle, to play an important role in the droplet existence. These quantum fluctuations allow a unique state of matter that connects opposite properties of gases, crystals and superfluids. This connection could be the path to a so-called supersolid, a spatially ordered material with superfluid properties.

Original Publication: Observing the Rosensweig instability of a quantum ferrofluid

http://arxiv.org/abs/1508.05007

http://dx.doi.org/10.1038/nature16485

 

Mentioned in the following news:

Der Standard: http://derstandard.at/2000030246368/Neuer-Materiezustand-Quantengas-Fluessigkeit-und-Kristall-in-einem

FAZ: http://www.faz.net/aktuell/wissen/physik-mehr/verrueckte-materieform-magnetisches-gas-wird-zum-fluessigen-igel-14098446.html

pro-physik.de: http://www.pro-physik.de/details/news/8887261/Auf_dem_Weg_zum_Suprakristall.html

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